5ₑ D＆D Vehicle Mechanics Supplementary Homebrew / House-Rules Options:

• vehicle maneuvers
• vehicle rules and limitations
• vehicle-repair

• Vehicles are a hallmark and mainstay of “Steampunk” or Dieselpunk settings, especially — but can be featured in many diverse fantasy settings at many technology levels anywhere advanced tinkerers or clever artisans are (or once were) present. When adventures take place on vehicles beyond uneventful travel, many DMs will undoubtedly use some version of “chase” or “skill-challenge” or more abstract / “theater of the mind” style rules and mechanics at many points and some scales of vehicular travel where that makes the most sense, but there will also undoubtedly also be points where vehicles and heroes or antagonists may be moving vehicles around on the grid during combat at normal scale, getting boarded or boarding airships or other flying contraptions or massive mounts, attacking targets on the ground from vehicles, moving from one vehicle to another, operating vehicles near hangers or docking-platforms or towers, etc. So, for these sorts of scenarios, some people may prefer some additional rules beyond RAW 5ₑ D＆D to handle those mechanics in some hopefully fun and dramatically cinematic ways…
  • Many complex vehicles cannot be operated competently by untrained characters without suffering disadvantage to any required roles (especially at anything beyond very cautiously slow speeds and/or in extraordinarily safe and ideal environmental conditions) except by experienced drivers or pilots with the relevant proficiency — and guided by a proficient navigator, if necessary, on any long or environmentally complex journeys… If not enough PCs are ace pilots or navigators, the party could always take on a few skilled hirelings — though of course without many class-levels/features they won’t be anywhere near as skilled as a heroic player-character could quickly become if expertly specializing in such skills.
• Depending on the setting, and how extensively vehicles will feature in it, one or more additional skills could be added to cover operating specialized vehicles (e.g. “Piloting” or “Driving” skills, both probably usually linked to Dexterity, and perhaps even “Navigation” or “Engineering” skills linked to other abilities). Alternatively, and more simply, vehicles can be handled as Vehicles “tool” proficiencies, adding Vehicles (Air) to the already existing Vehicles (land) as well as Vehicles (water) and thus allowing appropriately proficient characters to make checks with their proficiency-bonus to operate vehicles (with some difficult maneuvers or tasks disadvantaged or outright impossible for characters lacking proficiency).

MANEUVERS:

• Jump: Given a suitable ramp, terrestrial (and some aquatic, especially in case of waterfalls, waves, rapids, etc.) vehicles can jump a distance equal to ¼ of their current speed. They usually descend one inch (five feet) on the grid for every two inches (ten feet) jumped forward, so a vehicle jumping 20” falls 10” by the end of its jump.
• Obstacle (DC to avoid varies at DM discretion): Driving through a really tight obstacle looks easy enough on the tabletop since a vehicle is simply moved however the player wants. But (in-game “reality”) the vehicle is shifting around and is much more difficult to hold steady than the tabletop/grid shows. For this reason, drivers trying to pass through tight obstacles — narrow alleys, weaving and dodging between other vehicles, flying under cables, between cliffs or through canyons, etc. — must make Driving/Piloting rolls. DCs vary depending on the nature of the obstacle and difficulty to avoid. If the roll is failed, the vehicle hits the obstacle and suffers collision damage as usual.
• Ram (Opposed): Though we have to move vehicles in turns on the tabletop during combat, they’re actually moving simultaneously in the game’s “real world.” For that reason, when one vehicle rams another, we give the defender a chance to get out of the way if the opposing driver or pilot has a reaction he or she can use — even if it’s not his turn. When this happens, the two drivers/pilots make opposed Driving (or piloting, if airborne) rolls. If the attacker wins, he’s managed to ram his foe and damage is calculated normally. If the defender wins, he must move his vehicle just out of the way, whether backwards, forwards, or sideways such as with the 45º turn-template. Sometimes cars run into people or pedestrian creatures as well. In this case, the driver makes an opposed roll against the target’s Dexterity-save instead (with success avoiding the vehicle colliding with the creature).
• Tight-Turn: The vehicle can turn up to 90º instead of using the turning template as usual (45º for simplicity for most vehicles with significant forward momentum) while in forward motion, with a successful Driving or Piloting check; the distance drifted sideways as this turn is executed may vary depending on speed, but with a success generally should not exceed the total length of the turn-template (50feet or ten-grid-squares) except perhaps in case of a very large vehicle (the DC for this check depends on several factors, with a strong success generally substantially outperforming the turn-template and able to turn tightly or hit the mark of a new perpendicular forward vector accurately, such as turning into a narrow alley or canyon, whereas a failure would result in drift and a critical failure might send the vehicle out of control). Some vehicles can assist this maneuver by temporarily harpooning a stationary or very large moving object and using the cable to achieve a hairpin turn around it, at some point cutting or releasing the cable if they don’t wish to continue circling and wrapping around it; This can also be an excellent tactic to cripple walker legs, foul some varieties of airship rigging, or even potentially drag a vehicle into collision with some other vehicle or stationary obstacle; naturally, it could also turn a vehicle past 90º in one turn.
• Some flying vehicles (especially rotary craft) or automobiles can also instead optionally attempt to execute a 180º maneuver and about face while remaining in motion, which typically requires a Driving/Piloting check with disadvantage — if successful at the start of its turn, once successful, such a vehicle can decelerate at its normal rate while moving in reverse as part of the same movement, making movement in the opposite direction relative to that in which it was originally traveling in possible just as soon as it has enough acceleration/deceleration to reverse momentum (including perhaps on the same turn if the math works out), which is of course much more nimble than moving in circles on a 45º turn-template or even tighter 90º turns.
• Two-Wheels (or “sideways maneuver” such as a full or partial aileron-roll): Sometimes a character needs to put a wheeled vehicle or wide and ærodynamic winged-craft on its side, maybe to squeeze through a narrow alley or avoid running over some deadly obstacle, to squeeze through a narrow canyon, etc. Turning a vehicle up on two wheels requires a ramp of some kind — even an embankment or curb or some semi-compressible object can do the trick. The effect is to decrease the width of the car — usually by about 25%. The driver must make a Driving roll at the beginning of each turn he wants to keep the car up on two wheels — or a Piloting-roll to fly sideways between obstacles. A critical failure could hit an obstacle, scrape/slide the vehicle on the ground on its side in a barely controlled crash, or even flip the vehicle into an even more catastrophic slide or collision — depending on the DM’s ruling and the magnitude of the failure.
• powered-DIVE: roll Piloting with disadvantage while flying at top-speed; if successful, bleed ærium charge (or other lifting gas or similar mechanic appropriate to setting vehicles) and perform a powered-dive moving top-speed + ½ top-speed for one-turn and descending at the full rate of “climb” — then recover and stabilize/rebuild ærium charge at the start of next turn (assuming no damage to ærium engine) — or go “out of control” if the Piloting-roll is failed (this maneuver may only be available with certain vehicles with lifting-gas in certain settings)
• ballast-dump-power-CLIMB: roll Piloting while flying; if successful, emergency-dump ballast (such as water stores or prepared compartmentalized gas) and perform a powered-climb moving double-climb-speed for one-turn (assuming no damage to ærium engine) plus normal acceleration or top-speed forward as usual — or go “out of control” if the Piloting-roll is failed (this can usually only effectively be done once per encounter, and may only be available with certain vehicles with lifting-gas or flying-mounts capable of one extreme exertion between rests in certain settings)
• fuel-inject/supercharge-afterburner: roll Piloting while flying at top-speed; if successful, expend prothane (or similar setting appropriate fuel) and rocket forward at double top-speed for one-turn — or go “out of control” if the Piloting-roll is failed; this is a special ability of some outfliers or racing or interceptor fightercraft and typically must be refilled from a larger tank after use, so can effectively only be used once per encounter (this maneuver may only be available with certain vehicles with temporary speed-boost technologies or special mounts capable of one extreme exertion between rests in certain settings)
• OTHER Maneuver (the DM determines the DC based on any relevant modifiers): This one covers most everything else a driver, rider, or pilot might imaginatively try to do, such as going down a steep or slippery hill while maintaining control, avoiding a manhole cover or other obstacle, or driving through an oil slick at high speed, elaborate ærobatic maneuvers, etc. If the roll is failed, the driver goes out of control or some other adverse consequence results. Drivers or pilots are encouraged to narrate how they would like to cleverly or creatively attempt to avoid any potentially adverse consequence or challenge before the required roll and the DM should factor that plan into account in determining any DC.
• Unless an aircraft has the ability to hover (as most dirigible airships do), it must move half its acceleration or top speed to avoid descent or even a fall that may risk a collision landing if the descent is not successfully controlled (this especially applies to gliders) while in typical ærodynamic flight using wings.

VEHICLE RULES AND LIMITATIONS:

• VEHICULAR-ARMOR and HIT-POINTS: Especially while on the move with weak-points often difficult to easily access or attack, many vehicles are extremely tough or effectively nearly impossible for most infantry to straightforwardly or directly damage in combat without using heavy-duty vehicular weapons of their own, certain types of “magical” powers or weapons, called-shots or targeted strikes against specific vulnerable points (if any are accessible), or boarding and sabotage: attacking weak-points more directly and accessibly while aboard, or simply attempting to take control of the vehicle and crash it or take it a prize. Most Steampunk vehicles (especially more modern ironclad ones or even very large Kingdom Age “of sail” ones that are more antiquated) thus can often have quite a high AC due to very heavy armor as well as many hit-points — and are also immune from or resistant to (i.e. take ½ damage from) many common damage-types, including many “magically” produced damage types… SPECIFICALLY:
  • Most ironclads are immune to all bludgeoning, slashing, and piercing damage from most normal ranged or mêlée infantry sized weapons (which could generally do no more than slightly cosmetically dent them or scratch them insignificantly). Many other heavy vehicles are resistant (taking ½ damage), and may also have a “Damage Threshold” (DMGpage247) such that they cannot be damaged unless a single source of such common damage-types exceeds a certain amount of damage. The exception would be targeted attacks or called-shots (often made with disadvantage or subject to cover mechanics if not easily or directly accessible) to specific known vulnerable areas which could often have specific resulting effects and their own separate hit-points/damage-threshold/lesser-resistances/immunities (Intelligence: Engineering or similar check to know about where best to strike, or a lesser bonus if proficient at a relevant Repair skill, or can simply rely on common sense and give it a try). There’re also some “magical” weapons that could in most cases ignore these sorts of immunities or resistances, depending on their specific properties and damage type(s).
  • Most ironclads are immune to Cold attacks and many other vehicles are resistant. Many airships or industrial-strength working vehicles are designed to operate through quite severely frigid weather.
  • Most ironclads are immune or resistant to Fire attacks unless targeted at vulnerable weak-points sensitive to heat, which could then have a chance of catching fire and suffering ongoing damage. Civilian, antique, or luxury Kingdom Age (“Age of Sail”) style airships are much more vulnerable to fire, especially if targeted at some rigging or sail more flammable than the hull.
  • Many smaller or even some larger vehicles have a vulnerability (suffer double-damage) to Force damage (especially if targeted at a weak point). Many other tougher vehicles will be impacted by it normally.
  • Many smaller or even some larger vehicles suffer damage normally from Lightning damage — or may even have a vulnerability (suffer double-damage) to Lightning damage if targeted at a sensitive weak point such as delicate mechanisms or instruments by called-shot (disadvantage) or onboard sabotage.
  • Most vehicles are immune to Necrotic damage, unless they have materials that can be aged or decayed in some targeted way such as rotting canvas or rusting targeted weak-points (at the DM’s discretion).
  • Most mechanical vehicles are immune to Poison or Psychic damage unless living “mounts” and specified otherwise (or not mentioned) on their stat-blocks.
  • Many smaller or even some larger vehicles suffer damage normally from Radiant damage — or may even have a vulnerability (suffer double-damage) to Radiant damage if targeted at a sensitive weak point such as delicate mechanisms or instruments by called-shot (disadvantage) or onboard sabotage.
  • Many smaller or even some larger vehicles suffer damage normally from Thunder damage — or may even have a vulnerability (suffer double-damage) to Thunder damage if targeted at a sensitive weak point such as delicate mechanisms or instruments by called-shot (disadvantage) or onboard sabotage.
• Potential areas to target with called-shots on vehicles (assuming they’re accessible for attack and not covered from the attacker by armor or other interfering structures) include, but are not limited to: engines (ærium or prothane, the latter of which is potentially incendiary, and successful damage to engines that are not entirely destroyed should impede lift or acceleration by at least ½), other locomotion such as wheels or tracks (should typically impede speed by at least ½ if significantly damaged), controls (until a Repair-roll is successfully made, possibly including jury-rigged emergency repairs, this may prohibit some or all maneuvers or impede turns to at least one side if controls are damaged but not destroyed), a weapon or mechanism (a mounted heavy-vehicular-weapon or mechanism such as a cannon, flamethrower, winch, harpoon launcher, etc. is damaged to the point of no longer functioning without repairs, even if not completely destroyed), specific rigging or an lifting-gas ballonet could also be targeted (with varying effects depending on the nature of the vehicle), a crewmember on the vehicle with some exposure (with or without some degree of cover but not completely covered) could also be targeted (keeping in mind the fast-target rules and/or unstable-platform rules below), etc.
• Unstable Platform: Any character on an unstable platform, including most moving vehicles, suffers disadvantage to any targeted ranged-attacks (roll-to-hit) while on a pitching or swooping deck or to driveby/flyby mêlée-attacks against a target within reach that is not on the same or a similarly/parallel moving platform with the same relative-motion. This applies to characters who are firing vehicular weapons as well, though it does not apply to targets size huge or larger.
• Fast Target: A fast-moving vehicle or creature is more difficult to hit for a moving vehicle (or a character attacking from a moving vehicle), and imposes disadvantage on any attacks directed at it while the target is moving in excess of 5” speed (25feet per round). However, this is relative, so a vehicle heading directly toward or away from a character doesn’t impose disadvantage, nor does disadvantage apply if the attacker is shooting at a vehicle traveling parallel to his or her own at similar enough speed (DM’s call). This makes it more difficult to strafe targets when they’re moving quickly in a disadvantageous direction. Attacking head-on then swerving-away before collision — or, even more advantageously, moving up from behind a moving target is the best way to negate this issue if not able to match speed parallel to the target in order to fight “at broadsides” or move alongside for one traditional but risky method of boarding. If a vehicle is able to come to a complete stop or hover somehow, it can usually also make ranged attacks at moving-targets within range and line-of-sight normally unless they’re moving extremely fast and not directly toward or away from the attacker.
• Collisions can be very deadly in most settings (the DM would suggest bailing-out with parachutes or gliders whenever possible in case a serious crash seems inevitable and inexorable). The damage to the vehicle and its passengers is normally 1d6 for every 5” of its current speed (round down). If a motorcycle moving at 16” per turn hits a tree, for instance, it suffers 3d6 damage, as does its rider and anything it rams into. Safety-harnesses can ½ collision damage for occupants in certain types of vehicles or clipped to rigging in certain ways that can absorb some impact, if the DM determines that such technologies are available and they are in use at the time of the crash.
• Relative Speeds: Increase the damage if a vehicle hits another object moving toward it. This is called “relative speed.” If two armored-carts ram into each other at a speed of 12”, for instance, their relative speed is actually 24 and each armored-cart suffers 4d6 damage. Similarly, a vehicle moving away from an attacker subtracts its speed from the ramming vehicle’s speed to calculate the collision speed.
• Safety Harnesses: A seatbelt protects anyone wearing it. Roll ½ the normal damage dice (round down) for these characters. Do the same for cushioning-material bags, but also subtract one additional die of damage as well (it’s common for many freebooters on larger airships to jury-rig a “crash couch” somewhere in the hold with padded materials and some harness hookups nearby in case there is no other escape or parachute available).
• Soft Obstacles: The collision rules assume the vehicle has hit something hard, like another vehicle, rock, wall, and so on. If the obstacle was soft, like a person, the damage could be halved or negligible for the vehicle. The person takes damage normally, of course.
• Falling or Jumping From Vehicles: Characters who fall from a moving vehicle suffer damage just as if they were in a collision or fall (depending on speeds and how they jump). Jumping or falling into deep water needs to be considerably higher to begin to do major damage and should at most heights provide a Dexterity-save for ½ damage if the character can hit in a favorable body-position.
• Alternatively, if relative speeds are less a factor than relative sizes (such as a relatively much smaller creature or ship hit by a significantly more massive or gargantuan ship), or if looking for more quick and simple mechanics, then a crash with a larger vehicle that cannot be avoided by a Piloting or Dexterity save may result in full-damage for a failed save and ½damage for a successful one according to the following size/mass-based damage:
  • small = 1d6, medium = 1d10, large = 4d10, huge = 8d10, gargantuan = 16d10
• WRECKED: If “wrecked” while driving / flying, the driver or pilot (if any) must succeed on a Driving or Piloting save or the vehicle goes “out of control” with a randomly determined result… (this consumes the character’s reaction, if available, or else the check is automatically failed). Damage done to the vehicle by enough normal (not specifically targeted, called-shots, or sabotage which might have specific results faster) attacks exceeding its Damage-Threshold (if any) to the point that the vehicle is reduced to zero hit-points causes the driver or pilot (if any) to have to attempt to succeed on a Driving/Piloting save or else the vehicles goes “out of control” with a randomly determined result… At that point, many weaker or unlucky vehicles may automatically be “wrecked” — whereas, for tougher or “special” vehicles, each separate source of subsequent damage exceeding its Damage-Threshold (if any) is equivalent to failing a death-saving throw, with two failures if it suffers a critical-hit (and the possibility of instant-demolition for over max-HP damage in one hit). The vehicle goes out of control and is wrecked on three failures, and crashes if it’s an aircraft that was still flying at that point, with no chance of a successful enough crash-landing to not leave it wrecked (though the pilot or others may have a chance to use their reactions or other actions on their turns to attempt to bail out if they have parachutes or gliders, magical or other personal flight capabilities, etc.).
  • OUT-OF-CONTROL: 2d6
  • 2 — Rollover: The vehicle performs a Slip and rolls over 1d4 times in that direction. Roll collision damage for the  vehicle and everyone inside as appropriate. Any exterior-mounted weapons or accessories are broken and unusable until recovered / repaired.
  • 3↔4 — Spin: Move the vehicle 1d6” in the direction of the maneuver, or 1d6” away from a damaging blow. Roll a d12,  read it like a clock facing, and point the vehicle in that direction, moving it another 1d6” and resolving any collisions.
  • 5↔9 — Skid: Move the vehicle 1d4” left or right (in the direction of a failed maneuver, or away from a damaging attack).
  • 10↔11 — Slip: Move the vehicle 1d6” left or right (in the direction of a failed maneuver, or away from a damaging attack).
  • 12 — Flip: The vehicle flips end over end 1d4 times. Move it forward that many increments of its own length. Roll collision damage for the vehicle, its passengers, and anything it hits and resolve as appropriate. Slow and heavy vehicles such as huge armored-cars or mechs (DM’s discretion) may not flip, but suffer a Slip or Skid instead.
• REPAIR: Characters may repair vehicles given sufficient time and at least some basic tools as well as any necessary parts. This requires a Repair or a roll using one or more appropriate tool proficiencies (with the DC and time required variable depending on the extent and nature of the damage); a Repair-roll is usually made at disadvantage unless a character has and applicable proficiency (or at least proficiency with Intelligence: Engineering or familiarity with the vehicle type, and thus could typically attempt Repair without disadvantage but also without Proficiency-bonus or with ½ bonus at best, depending on the task, if no proficiency is precisely applicable). Fieldwork requires at least an appropriate toolkit and basic supplies, and generally has a higher DC than fixing things more slowly and carefully as well as with more space/easier-access at a suitable dedicated repair facility. An average hanger/garage or close proximity to such a workshop negates this penalty, and an excellent and well-stocked or specialized/dedicated facility adds at least +1 to the Repair-roll or even gives advantage if expert assistance/advice is available for consultation. Wrecked vehicles or vehicle systems/components take more time and decent quality parts to be able to repair or convert from salvage to usable, assuming they were not entirely demolished beyond recovery to the point of scrap. Obviously, the DM has final say regarding to what extent (or if) any wrecked vehicle can be salvaged or adequately repaired, depending on how it wrecked — but the preceding rules should provide ample guidance for DMs and players to collaborate and decide on reasonable repair mechanics that make most plausible and feasible sense for the setting, story, and resources available to the adventuring party, and players’ creativity or ingenuity should generally be rewarded.

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