For a truly FAST Pinewood Derby car there are three key areas that must be properly aligned, failure to do so.....
LEAVES SPEED ON THE TRACK!
Key Alignment #1 - Rear Wheels
Rear wheels at a 3 degree angle (camber). This greatly reduces friction as only a tiny portion of the wheel is making contact with the track. Plus, the angle makes the wheels rub against the axle head rather than the car body, greatly increasing speed. The axle holes (and therefore the wheels) must be at the same height, precisely parallel to each other.
Rear wheels must be perpendicular (90 degrees) to each other and to the car body. Additionally, the wheels must be directly across from one another.
If rules allow, the rear axle holes should be placed 5/8ths (0.625) of an inch from the rear of the car. This increases stability and maximizes the amount of weight that can be placed in the rear of the car.
If the wheels are not parallel and perpendicular to each other, they will be in a toe-in or toe-out orientation, or a combination of these two. Any of these positions will significantly slow the car.
Key Alignment #2 - Fore/Aft
For maximum speed the front and rear of the car must be level with each other. This can be measured by comparing the distance to the track (or other flat surface) at the front and back of the car.
However, to increase stability and guard against speed-killing wiggles the fastest Pinewood Derby cars will steer (or drift) into the center rail. This is accomplished by canting the front wheel at an angle (negative camber) and by turning the wheel slightly (toe in).
Canting and turning tilts the wheel and raises the front of the car.
This is an issue. When the front of the car is higher than the rear, it causes a toe-out orientation on the rear wheels, increasing friction and killing speed.
To eliminate this problem the front axle hole must be placed at a PRECISE amount higher than the rear axle holes ensuring that the rear wheels are not placed in a toe-in or toe-out position.
Key Alignment #3 - Side to Side
The car steering into the rail creates an issue, with the front wheel rubbing the rail the rear wheel will do the same, increasing friction.
To eliminate this problem and maximize speed, the front of the body where the wheel is attached is cut in a PRECISE amount enabling the rear wheels to be an equal distance from the center rail. This ensures the rear wheels do not go down the track slightly sideways, increasing friction and killing speed.