There are detailed rules with examples in the above document, but here is a quick reference:
First person over the finish line after 3 laps wins.
Turn order is based on the current positions of the cars, the person in first place rolls first etc. During your turn you select a gear, either one higher or one or more lower then the gear you were in at the start of your turn, based on your gear you roll a die, the higher the gear the larger the die you roll.
You must move a number of spaces equal to the number you rolled, on straights you're not allowed to zig-zag except to avoid cars or obstacles (basically you have to follow the shortest safe path possible) and in corners you're only allowed to move according to the arrows painted on the board, if a move is partially on a straight and partially in a corner they're treated separately. Every corner has a certain number of stops you must make, not stopping enough times will either cause damage to the car if you miss one stop or crash out of the race is you miss more than one. When necessary you can use breaks to move less than the number of spaces you rolled at the cost of damage.
You start 20 wear points in total on the car +2 more in the pits you can use for repairs during the race, you can divide these points as you see fit (at least 1 in each category, max 14 tyres, max 7 on any other part) at the start of the race or use the standard point spread:
Tyres: 6
Breaks: 3
Gearbox: 3
Bodywork: 3
Engine: 3
Suspension: 2
Different actions may cause you to take damage to different categories:
Overshooting:
When missing a mandatory stop in a corner you take 1 point of tyre damage for every space you overshoot, if you miss two mandatory stops in a corner you crash out of the race entirely. Note: when overshooting you're not allowed to change lanes and if you enter the next corner it does not count as one of your mandatory stops in that corner.
Breaking: You may move less spaces than you rolled, spending a break point for every space you move less to a maximum of three.
Blocking: If you move into the back of another car and cannot change lanes you lose break and tyre points equal to the amount of squares you still have to move, you first lose up to three break points and then up to three tyre points, if you don't have enough break or tyre points or you have 7 or more spaces left to move you crash out of the race. Note: You can use a break action before blocking effectively using up to 6 break points.
Gearing down: You may shift down one gear per turn without any damage, if you shift down 2 gears you take 1 gearbox damage, 3 gears, 1 gearbox and 1 break, 4 gears 1 gearbox, 1 break and 1 engine, you cannot shift down 5 gears.
Collisions: If you end your turn next or behind another car you may cause a collision, both players roll a d20 and on a 1 you take 1 bodywork damage.
Engine: If someone rolls a 20 in 5th gear or a 30 in 6th after you've moved every player currently in 5th or 6th gear rolls a d20 and takes a point of engine damage on a 1-4.
Road handling: If you move over a hazard space you roll a d20 and lose a point of suspension on a 1-4.
Different types of damage affect the car differently.
Tyres: If you run out of tyre points exactly you spin out, restarting your car on the next turn in 1st gear and resetting your tyre points to 1. If you lose more tyre points than that you crash out of the race.
Brakes: If your run out of break points you can't break or use any other action that uses break points.
Gearbox: If you run out of gearbox points you cannot shift down more than 1 gear per turn.
Bodywork: If you run out of bodywork points you crash out of the race, every time you take a point of bodywork damage the tile you're on becomes hazardous for the rest of the game.
Engine: If you run out of engine points you must make one more move in 4th gear and then crash out of the race, unless you're in the penultimate (2nd to last) corner or further on the final lap, then you're allowed to try to complete the race, but have to shift down every turn. Every time you take a point of engine damage the tile you're on becomes hazardous for the rest of the game.
Suspension: If you run out of suspension points you crash out of the race.
Pit stop: You can go into the pit lane at the end of a lap. You move there as normal, though you can't take damage. If you reach your own pit stall you go in for your pit stop, you get all your tyre points back immediately and can then choose to repair up to two damage to other parts of the car. If you only change tyres roll a d20, on a 10 or less you immediately move that number of spaces divided by 2 in 4th gear, if you roll 11 or higher or if you repaired other parts of the car you stay in the its and start next turn in any gear up to 4th.
Slipstreaming: If you're in 4th gear or higher and end exactly behind a car that is also in 4th gear or higher and you're in the same or higher gear than them you may slipstream and move 3 more spaces, if you enter a corner through slipstreaming you lose 1 break point. You may not slipstream after breaking, though you may break after slipstreaming.
Qualifying:
To determine starting positions every player does a qualifying round. You start alone on the middle of the start/finish line (every player gets their own thread) and try to complete a lap in the least rolls possible, you do not take damage during qualifying and if you crash out you still start the race, just in last place. You're not allowed to break and any tyre damage you would have taken is counted against your score. The person with the lowest score gets first place on the starting grid etc.
Weather and tyre compounds:
At the start of qualifying and the start of the race a die is rolled for the weather conditions, the weather can be sunny, rainy or changeable causing the track to be dry or wet. On a dry track the rules are as described, on a wet track the road is more slippery causing problems with movement and affecting damage rolls.
At the start of qualifying and of the race and during pit stops you choose a tyre compound to race on, hard, soft or rain.
Hard: On a dry track this tyre compound does nothing special, on a wet track you must add +3 to your roll on any mandatory corner stop.
Soft: On a dry track you may choose to add +1 to your roll after every roll during your first lap, on a wet track you cannot use this bonus and you must add +3 to your roll on any mandatory corner stop. In addition in both dry and wet conditions you take double tyre damage/penalties on your first two laps with this compound and 3x on your third lap.
Rain: On a dry track you take double tyre damage/penalties on your first two laps with this compound and 3x on your third lap, on a wet track you take normal damage and you only have to add +1 to your roll on mandatory corner stops.
