D20 driving rules

[HUMVEE Driver]

I've been making my own extensive D20 driving rules for quite a while now, and I looked around the forums for anyone else doing the same. Didn't find anything. So, is there anyone out there doing something similar? I'm wondering what others came up with.

[firemagehao]

Any system in particular? I know d20 Modern has them.

[HUMVEE Driver]

D20 Modern driving rules suck, IMHO. Fairly confusing, very unrealistic, and not enough variety.

I wanted something that would allow for a lot of realism while at the same time being easy and fast to use. I'm confident that I've accomplished that, and I want to see what others have come up with (if at all).

*Also, my rules are actually geared toward a Mad Max style of gameplay; lots of road combat.

[firemagehao]

Could you post it for critique?

[HUMVEE Driver]

Here it is. I don't have all the charts handy, and I am well aware that soem things may need to be hashed out. I need play testing for that, which (sadly) I'm unable to find players for.

Any and all input is appreciated!





MAPPING/GRID SQUARES: For gaming purposes, most vehicles are considered to be 10x10 feet. Each grid square is also 10x10 feet. Some vehicles may be larger, such as buses and tractor trailers.

INITIATIVE WHEN DRIVING: Sometimes a driver may wish to delay his turn, in order to see what opposing drivers are doing and thus set himself up to attack them. A driver may delay his action up to the negative of his Initiative roll. So an Initiative roll of 16 may be delayed until the count of -16.

VEHICLE RESPONSIVENESS: Vehicle responsiveness is a vehicle’s ease of operation and maneuverability, as well as how fast a vehicle can accelerate or brake. A driver can do more with a Manual Transmission than an Automatic Transmission, and a motorcycle is much more agile than a bulldozer. When a vehicle is first built it is given a Vehicle Responsiveness Modifier. Age, mileage, and damage can reduce a vehicle’s responsiveness. Vehicle responsiveness is expressed as a modifier to certain die rolls and skill checks. It comes into play when making Drive Checks, and when attempting Stunts. Some very large vehicles may have a negative Vehicle Responsiveness Modifier. Regardless of this, all vehicles accelerate and brake at least 10 MPH per round.

DRIVE SKILL AND VEHICLE RESPONSIVENESS MODIFIER: Your character will usually be driving the same vehicle, so feel free to just add your vehicle’s Responsiveness Modifier to your Drive Skill for ease of gaming. Just be sure to change it if your character changes vehicles!

LANE CHANGES: Any time a vehicle voluntarily wishes to change a lane, it ‘costs’ one square of movement to do so. Then the vehicle moves one square forward and one square to either side, thus using two squares of movement.

TURNS: To make a turn, a drive check must be made vs the tightness of the turn. When driving at the speed the road was designed for, no drive check is necessary (unless the vehicle is damaged in some way, poor road conditions, etc). When driving over the speed limit, add the vehicle’s current speed modifier to the DC and use this chart:
35 degree turn: DC 10
45 degree turn: DC 15
90 degree turn: DC 20
180 degree turn: DC 30

RAMMING POSITION MODIFIER: Ramming into a car from behind is easier than slamming on your brakes and forcing your opponent to ram into you. Therefore attacking from behind grants a +2 to your Drive Check (attack) and attacking from the front carries a -2 penalty.

SPEED MODIFIER: The Speed Modifier is very important, as it applies to just about everything characters do while in a moving vehicle. When two vehicles are attacking each other you use the difference in their two Speed Modifiers. When two vehicles are moving directly towards each other, you add their two Speed Modifiers together. A vehicle’s Speed Modifier applies when:
-Making Drive Checks except while under normal driving conditions
-Making a Drive Check to ram another vehicle
-Making a Drive Check to regain control of your vehicle
-Making ranged attacks from a moving vehicle

AC MODIFIER: A moving target is harder to hit than a stationary target. To show this, a vehicle is given a bonus to its AC, depending on how fast it is moving. A vehicle’s AC Modifier applies to all occupants of the vehicle as well as the vehicle itself. Just like the Speed Modifier, when two vehicles are driving along with their crews shooting at each other you use the difference in their two AC Modifiers.

SHOOTING FROM A VEHICLE: The base modifier for shooting from a moving vehicle is -4, no matter what speed the vehicle is moving. This represents the rocking and bouncing (no matter how minor) that a person in a vehicle is subject to. Apply the vehicle's current Speed Modifier plus the -4 to your attack roll any time you wish to make a ranged attack while in a moving vehicle. Note that when a character in a moving vehicle wishes to shoot at another moving vehicle, you apply the DIFFERENCE in the two vehicle’s Speed Modifiers. Shooting while driving counts as attacking with two weapons. The Two Weapon Fighting feat applies here, as well as using a light weapon. Drivers may shoot at any time during their movement (before you move, during your movement, or at the end of your movement). Passengers may shoot on their Initiative count as normal.

COVER FROM A VEHICLE: Car doors offer a +4 cover bonus to a character’s AC. Ducking behind a door gives total cover.

GETTING STARTED: Each driver (and passengers, if any) should get into their vehicles. Entering a vehicle is a Move Equivalent Action, while convertibles and motorcycles can be entered as a Free Action. Starting a vehicle is also a Move Equivalent Action. A Tumble Check (DC 12 for most vehicles) can be made to jump through a vehicle’s window (assuming the window is rolled down!) and thus enter the vehicle as a Free Action. Failure means the character has somehow missed and fallen to the ground and must stand up the next round. A Drive check (with the vehicle’s Responsiveness Modifier) can be made to Quick Start a vehicle as a Free Action. Failure means the vehicle doesn’t start and must be tried again the next round.

Once a vehicle is running, a driver may simply drive away without making Drive Checks. However, if a driver wishes to try and push his vehicle beyond its normal capacity, he may attempt Stunts, covered on the STUNTS page.

BODY PANELS: Almost all vehicles are made with body panels. A vehicle’s body panels offer damage reduction to shooting attacks from any angle and ramming from the sides. Body panels have a Damage Reduction of 5 and a break DC of 10. Taking off the body panels gives a bonus to speed and fuel economy, but also (obviously) removes the damage reduction. Enemies can try to rip off the doors with certain attacks, such as with a grappling hook. Only doors without windows (rolled down or shattered) may be removed in this way. Ripping off body panels does not reduce a vehicle’s Damage Reduction to ramming. It only removes the cover bonus from the occupants and/or critical components.

RAM ARMOR: Ram Armor usually comes stock on a vehicle, and there are many ‘aftermarket’ parts that act as Ram Armor. Ram Armor offers damage reduction to ramming attacks only, and it cannot be forcibly removed by enemies. Some typical Ram Armor:
Hardness Hit Points
-Bumper (front or rear): 5 5-10
-Running Boards 5 5-10
-Trailer Hitch 10 10-15


VEHICLE ARMOR: Plate steel can be welded or bolted to a vehicle to give it better protection. A character’s Build/Repair skill determines how strong the armor is and how well it holds up to punishment. Vehicle Armor gives damage reduction to both ramming and shooting attacks. Enemies can try to rip off Vehicle Armor with certain attacks, such as with a grappling hook. Vehicle Armor can be mounted anywhere on the vehicle. Vehicle Armor slows a vehicle and reduces its fuel economy. Some typical Vehicle Armor:
Hardness Hit Points Break DC
-Side armor: 10 10-15 25
-Front ram plate: 10 15-30 30

Note that Vehicle Armor stacks with Body Panels and/or Ram Armor. So a truck with a front ram plate has Damage Reduction of 20 (10 from the Bumper +10 from the ram plate) plus whatever hit points the front ram plate has. So with a 1 inch thick front ram plate (30 HP), the truck in this example can withstand 49 hit points worth of damage when attacking vehicles from behind before losing its ram plate, and it ignores any damage less than 20. Ram away!

SPIKE ARMOR: Spike Armor offers no damage reduction, but it allows the vehicle to deal more damage when it is involved in a ram. Spike Armor can be mounted anywhere on the vehicle. A vehicle with Spike Armor deals an extra 2d6 when it rams or is rammed by another vehicle.

WINDOWS: One of the first things to be shot out in any road battle are the windows. Windows only offer protection from shooting attacks. Windows have a Hardness of 1 and 1 Hit Point. If a window is shot out, the remaining damage is inflicted on whatever occupant was hit (if any). A windshield is just like any other window, except it is much tougher. Windshields have a Hardness of 3 and 3 Hit Points.

TIRES: Average tires have a Hardness of 3 and 5 Hit Points. Big truck tires have even more. Tires are immune to bludgeoning damage. Because they spin at such high speeds, tires cannot be armored. (Any armor on a tire would overburden and unbalance it, making the tire wobble and soon become useless.)

DISABLING A VEHICLE: There are two ways to disable a vehicle:
- By ramming the vehicle and dropping it's Structural Integrity Hit Points to 0.
- By destroying one or more of the vehicle's critical components, such as shooting the radiator and reducing its Hit Points to 0.

RAM ATTEMPT: A Ram Attempt is when one vehicle tries to ram another vehicle. Both vehicles are dealt damage, and their respective Damage Reduction from armor (if any) applies. The target vehicle may be forced off-road, into a barrier, another vehicle, and/or Out Of Control.

How it works: The attacking vehicle simply moves into the target vehicle's square(s). The attacking vehicle's driver makes a Drive Check vs the target vehicle's driver's Drive Check.

If successful: The attacking vehicle moves into the square occupied by the target vehicle, and both vehicles take damage to their respective Structural Integrity scores. Each vehicle's Damage Reduction applies. The target vehicle is then Out Of Control (see below) and must regain control on its next turn. The DC to regain control is the damage taken after any Damage Reduction is applied.

If unsuccessful: Again, the attacking vehicle moves into the space occupied by the target vehicle. The target vehicle has the choice to either allow itself to be hit, move in front of, behind, or to the side (lane change) of the attacker if there is room to do so. If the target vehicle is surrounded by other vehicles, the target vehicle automatically moves into one of their spaces (target vehicle's choice). It is then up to the vehicle in said space to make a Drive Check on his turn to avoid being hit by the target vehicle. The target vehicle is essentially making a Ram Attempt on the other vehicle.

RAMMING DAMAGE: Damage as a result of one vehicle ramming another is calculated by:
- 2d6 per difference in Speed Modifier (minimum 2d6) + 2d6 per difference in Weight Modifier (minimum 2d6)
*See chart
This damage is applied to the vehicle's Structural Integrity Hit Points.





STUNTS - Drive check vs. Stunt DC + Speed Modifier

Avoid Hazard: Used when entering a square occupied by an object. Failure indicates a collision with the object.
- Caltrops 15 + Speed Modifier
- Oil Slick 15 + Speed Modifier
- Small Object 5 + Speed Modifier
- Medium Object 10 + Speed Modifier
- Large Object 15 + Speed Modifier

TURNS: To make a turn, a drive check must be made vs the tightness of the turn. When driving at the speed the road was designed for, no drive check is necessary (unless the vehicle is damaged in some way). If the driver can change lanes to the outside of the curve, the DC is reduced by -2 for each lane. If the driver tries to change lanes to the inside of the curve, the DC is increased by +2 for each lane. When driving over the speed limit, add the vehicle’s current speed modifier to the DC and use this chart:
- 35 degree turn: DC 10 + Speed Modifier
- 45 degree turn: DC 15 + Speed Modifier
- 90 degree turn: DC 20 + Speed Modifier
- 180 degree turn: DC 30 + Speed Modifier

Bootleg Turn: Rapidly come to a complete stop facing in a new direction. This stunt includes a Hard Brake. Failure indicates automatic Slip or worse (see below)
- 90* 18 + Speed Modifier
- 135* 22 + Speed Modifier
- 180* 26 + Speed Modifier

Power Shift: Push a vehicle to accelerate at 150% its normal capacity. Failure indicates acceleration at 50% capacity.
15 + Speed Modifier

Hard Brake: Push a vehicle to brake at 150% its normal capacity. Failure indicates braking at 50% capacity.
15 + Speed Modifier

Hard 45* Turn: Move a vehicle at half of its movement before turning instead of full movement. Failure indicates no turn.
15 + Speed Modifier

Shake Off: Used to shake opponents off of a vehicle. Forces a Clamber Check vs DC 15 + Speed Modifier. Failure indicates automatic Slip or worse (see below).
15 + Speed Modifier

FAILURE – Regain Control = DC 10 + Speed Modifier
Failure indicates that a vehicle is Out Of Control. The vehicle's driver must regain control (by beating the DC for the original check) before taking any other actions. (Failure while turning automatically moves the vehicle to the outside of the turn.)
Failure by:
5 or less – Slip: Automatic lane change 50% right or left, -4 to Drive Checks until successful Regain Control.
6-10 – Slide: Two automatic lane changes 50% right or left, -8 to Drive Checks until successful Regain Control.
11-15 – Spin: Three automatic lane changes 50% right or left, -12 to Drive Checks until successful Regain Control. Vehicle spins to a stop at normal braking speed unless successful Regain Control.
16 or greater – Roll: Vehicle rolls to a stop at automatic Hard Brake speed. 40% chance of landing upside down, 40% chance of landing on wheels, 10% chance of landing on right side, 10% chance of landing on left side. Each Round the vehicle components and crew take 1d6 damage per Speed Modifier. This damage is halved if the crew are wearing seatbelts.

[HUMVEE Driver]

I did some play testing in a post apocalyptic setting (with firearms being somewhat scarce). It seemed that most player's prefered method to stop a vehicle is by boarding and killing the crew instead of trying to disable the vehicle by shooting out its tires or ramming it to a stop.

Again, I wish I had more play testers!

[firemagehao]

That is... Bookmarked. I will remember this for the next modern-era game I play in.

[HUMVEE Driver]

I would REALLY like to hear how it goes, and I appreciate your interest! I'll get the rest of the info up ASAP.