Here is something to drive in the post-apocalyptic wasteland, inspired by this.
Hit dice (HD) work the same for vehicles as they do for creatures.
Seats denote how many people can normally use the vehicle. More people can hang on, but any risky manoeuvre forces them to Save or fall off, and any damage taken by the vehicle is also taken by them.
Cargo is the number of inventory slots you can store in the vehicle. Various upgrades can also be installed into cargo slots.
Fuel is a usage die rolled for every overland turn spent travelling (wait for hexcrawling rules), and for every risky situation you get yourself into. Every time you roll a 1, decrease your fuel reserve by one category. Using a canister of fuel conversely increases your reserve by a category.
Empty > Low Fuel > Full Tank
Weight is rather obvious. Heavy vehicles are generally better for car combats.
Speed marks the maximum speed the vehicle can go. All vehicles accelerate one speed category per round, so a Fast vehicle would need three rounds to reach its max speed, and slow by halving their speed.
Light/Slow > Mid-Weight/Speed > Heavy/Fast > Very Heavy/Fast > Super-Heavy/Fast
Defense of a vehicle is based on its current speed: Unarmoured while standing still, as leather at Slow speed, as chain at Mid-Speed, as plate at Fast speed, and then +1 per category. Roll a driving check instead of Attack when using a vehicle as a weapon.
Vehicles do not use separate actions to attack, but rather move to ram or overrun. This causes damage depending on the vehicle's weight or current speed, whichever is better, 1d6 damage per category. If one vehicle is heavier than the other, decrease the damage against it by the difference in weights. Vehicles take no damage for running over soft targets (like people).
For example, an SUV rams a chopper. The SUV goes at its max speed, dealing 2d6 damage. The chopper is still picking up seed, going only Mid-Speed, so it would deal the same damage as the SUV, but because of the weight difference this is decreased by one category, resulting in 1d6 damage.
When a vehicle runs out of hp, it is
Wrecked. If currently moving, the driver must make a driving check to crash safely. Passengers normally take no damage until their vehicle runs out of hp, but crashing may cause them damage based on the vehicle's speed. Vehicles can be repaired with spare parts during downtime.
Sidesweeping deals half damage and forces a driving check from the lighter vehicle to avoid crashing. Driving check may also be called for in risky situations, and failure may cause damage to the passengers.
Mechs could use similar rules.
Roll d6 for a biker gang, d10 for motorized raiders, and d20 for a motley crew of randomly scavenged vehicles.
d20 Vehicles
- ATV: HD 2, Seats 1, Cargo 10, Fuel 1d12, Light, Mid-Speed
- Buggy: HD 2, Seats 2, Cargo 10, Fuel 1d8, Light, Fast
- Chopper: HD 2, Seats 1, Cargo 5, Fuel 1d10, Light, Very Fast
- Dirtbike: HD 2, Seats 1, Cargo 5, 1d12, Light, Fast
- Motor Trike: HD 2, Seats 2, Cargo 10, Fuel 1d10, Middleweight, Fast
- Sidecar Bike: HD 2, Seats 3, Cargo 5, Fuel 1d10, Light, Mid-Speed
- Cabriolet: HD 3, Seats 4, Cargo 30, Fuel 1d8, Middleweight, Fast
- Jeep: HD 4, Seats 4, Cargo 30, Fuel 1d10, Middleweight, Mid-Speed
- Pickup: HD 4, Seats 6, Cargo 40, Fuel 1d10, Heavy, Slow
- Sportscar: HD 3, Seats 2, Cargo 20, Fuel 1d8, Middleweight, Very Fast
- Semi Truck: HD 5, Seats 4, Cargo 20 (200 with trailer), Fuel 1d8, Very Heavy, Slow
- SUV: HD 3, Seats 5, Cargo 30, Fuel 1d10, Middleweight, Mid-Speed
- Van: HD 4, Seats 6, Cargo 40, Fuel 1d8, Heavy, Mid-Speed
- Bus: HD 5, Seats 20, Cargo 60, Fuel 1d8, Very Heavy, Slow
- Skiff: HD 3, Seats 4, Cargo 20, Fuel 1d10, Light, Fast, aquatic
- Yacht: HD 6, Seats 10, Cargo 50, Fuel 1d8, Heavy, Slow, aquatic
- Helicopter: HD 3, Seats 2, Cargo 10, Fuel 1d8, Middleweight, Super-Fast, flying
- Hovercar: HD 3, Seats 4, Cargo 20, Fuel 1d6, Middleweight, Fast, flying
- Armoured Transporter: HD 8, Seats 10, Cargo 30, Fuel 1d8, Super-Heavy, Mid-Speed
- Tank: HD 10, Seats 4, Cargo 10, Fuel 1d6, Super-Heavy, Slow, chain cannon
And for the truly desperate: Segway: HD 1, Seats 1, Cargo 0, Fuel 1d10, Light, Slow.
Upgrades do all sorts of crazy things, but it should not be easy to find them. Roll 1d20 for relatively common upgrades, 2d20 for uncommon and 3d20 for rather rare upgrades.
Upgrades:
- Extra Fuel Tank: 3 Cargo, step up Fuel die.
- Extra Seat: 5 Cargo, +1 Seat.
- Turbo: 3 Cargo, temporarily increase speed one category above max, but also decrease Fuel reserves.
- Airbags: 1 Cargo per Seat, negates one instance of damage to passengers.
- Float Bags: 5 Cargo per weight category, the vehicle floats on water rather than sinking.
- Improved Shock Absorbers: 2 Cargo, +1 to driving, stackable.
- Radio Receiver: 4 Cargo, for remote communication.
- Heavy-duty Frame: half max Cargo, +1 HD.
- Harpoon: 5 Cargo, 1d8 damage and reel-in chain, range 50 m.
- Spikes: 5 Cargo, heavier vehicles don't get decreased damage.
- Wheel Blades: 3 Cargo, sidesweeping deals full damage.
- Plough: 6 Cargo, use d8 for ramming damage.
- Flamethrower: 5 Cargo, 2d6 fire damage and Save vs catching fire, range 30 m cone, out of fuel on any 1.
- Claw Crane: 10 Cargo, can lift heavy objects.
- Five-point Harness: 1 Cargo per Seat, prevents damage from failed driving checks.
- Searchlight: 4 Cargo, powerful light.
- Secret Stash: 2 Cargo, half your Cargo can be hidden in secret compartments.
- Steam Engine: 10 Cargo, can use wood/coal and water instead of petrol/diesel.
- Camouflage: 6 Cargo, hides the vehicle when stationary.
- Plasteel Plating: 5 Cargo, gain DR 3 (does not stack).
- Stereo System: 3 Cargo, for really loud music.
- Bed: 10 Cargo, provides a comfy bunk.
- Minifridge: 4 Cargo, keeps your food cold.
- Kitchen Unit: 10 Cargo, cook your meals without a camp.
- Water Purifier: 5 Cargo, makes polluted or brackish water drinkable.
- Onboard Lab: 20 Cargo, equipment and chemicals to make your drugs or explosives.
- Medical Unit: 20 Cargo, helps with treating injuries.
- Forklift: 8 Cargo, can lift heavy objects.
- Roller Drum: 6 Cargo, use d10 for ramming soft targets.
- Security System: 3 Cargo, failing to unlock the vehicle deals 1d8 electric damage.
- Alarm System: 3 Cargo, motion sensors linked to sirens.
- Solar Panel: 5 Cargo, generates 1 Energy per hour of sunlight.
- Ejection Seat: 5 Cargo, activate to shoot yourself out of the vehicle.
- Computer Terminal: 8 Cargo, all the computing power you might want.
- Recharging Station: 1 Cargo, roll Fuel dice to recharge 1 Energy for a gadget.
- Weather Station: 5 Cargo, measures wind, humidity, radiation etc. and helps in predicting dangerous weather.
- Self-destruct System: 2 Cargo, with a remote control you can carry.
- Autopilot: 4 Cargo, the vehicle will keep to its course if you stop steering it.
- Duralloy Plating: 10 Cargo, gain DR 6 (does not stack).
- Navigation: 4 Cargo, decrease chance of getting lost by 2.
- Jet Engine: 10 Cargo, increase Speed by two categories, but decrease Fuel die by two steps.
- Minireactor: 20 Cargo, set Fuel die to d20, but can only be refuelled by uranium rods, antimatter, dark matter, or something similarly rare and dangerous.
- Plasma Turret: 10 Cargo, 2d8 fire damage, range 150 m, out of ammo on any 1.
- Laser Turret: 5 Cargo, 1d10 radiant damage, range 200 m, out of energy on 1.
- Minigun: 5 Cargo, 1d12 damage, range 100 m, out of ammo on 1.
- Machinegun: 15 Cargo, 4d6 damage, range 100 m, out of ammo on any 1.
- Coilgun: 20 Cargo, 6d6 damage, range 100 m, out of ammo on any 1.
- Grenade Launcher: 10 Cargo, damage per grenade, range 150 m.
- Rocket Launcher: 15 Cargo, 2d10 fire damage, seeking missiles, range 150 m, out of ammo on any 1.
- Water Cannon: 5 Cargo, 1d6 damage and Save vs knockback, range 30 m cone, out of water on 1.
- Chain Cannon: 20 Cargo, 3d10 damage, range 200 m, out of ammo on any 1.
- Particle Cannon: 30 Cargo, 4d10 damage, range 200 m, out of ammo on any 1.
- Laser Array: 15 Cargo, 1d20 radiant damage, range 200 m, out of energy on 1.
- EMP Blaster: 10 Cargo, 2d10 damage vs electronics, range 50 m cone, out of energy on any 1.
- X-ray Blaster: 15 Cargo, 3d8 radiation damage, range 50 m cone, out of energy on any 1.
- Targeting System: 8 Cargo, +4 to hit with mounted weaponry.
- Antigrav Thrusters: 8 Cargo, +4 to jumps with the vehicle.
- Scanners: 5 Cargo, detect technology within the hex.
- Shield Generator: 20 Cargo, force field grants DR 10, runs out of energy when any damage gets through.
- Gravity Manipulator: 5 Cargo per weight category, with a driving check you can ride on walls.
Of course, you can also get rid of seats for extra Cargo, install more upgrades on the roof, or anything else your GM lets you. Go crazy.