I'm assuming they are a little more sophisticated about weighing the
cars these days. Am I right?

Yep, every car is weighed on the same digital scale which is calibrated
from use to use with a 'standard' 5 oz weight to make sure it's
calibrated the same no matter which day the kids register their cars.

Cars also have to be registered no later than 1 week before the race
and they are confiscated until race day. The guy in charge doesn't have
any kids so their's no partiality involved.

And if one of the kids car is over weight or under weight, we have a
few drill presses setup and either one of the volunteers can adjust the
weight or one of the kids parents can.

And I'll be happy to post the results once we start testing.

Tillman