Design Tips
1)     Have your son draw a design on paper then cut it out and use it
as a template. I use graph paper.  Draw a side and top view on the
paper by tracing around the block of wood.

2)     Keep the car a full seven inches. It has to do with the physics
of velocity and length of travel of the weights.

3)    Use the full 2 3/4 inches (outside wheel to outside wheel) that
the rules give you. This will allow the wheels to travel farther
before hitting the center strip.

4)    Leave a lot of wood in the back to put in the weights.  Aim for
a center of gravity about 1 & 1/2 inches in front of the back axle.  You can try
further back, but the further back the more unstable the car becomes.

5)     Use the groove closest to the end of the block of wood as the rear axle.

Note: The Race Starter will place the car on the track according to
axle location.  The back axle is nearest to the end of the car.  The
front axle is furthest away from the end of the car.  This determines
the direction the car will race unless the contestant clearly marks
"Front" on the car.

6)    Do not make the front of the car too pointed (leave at least ½
inch width). It is hard to set up against the starting dowels.

7)    Use your imagination. Be creative. Shape has the least to do
with winning. A beaver driving a log or even a pickup truck is more
interesting than a wedge and will be just as fast.  The aerodynamics
of a small block of wood doesn't mean much in thirty feet.

8)    “3” wheel vs “4” wheel – 3 wheel cars are faster BUT only if the
4th wheel NEVER contacts the track.  This works well on metal tracks
but may not work on our wooden track.

9)    Axle slots vs drilled holes – axle slots like to split.
Pre-drill the axle slots if you have access to appropriate tools
(drill press or an appropriate jig).  Grinding burs from the pointed
ends of axles also helps.  Epoxy/glue the axles in place (must be
transparent to pass district inspection - entire axle visible).

10)  The following link is an easily understood video on the science behind pinewood