Our pack goes a little overboard with it and it is a bit too competitive for my taste which means every year my son has to do a bit more to be competitive. He finished first this year out of 50 or so cars.
Our pack has an aluminum six lane track with all kinds of electronics, remotely controlled gate, 3 cameras with instant replay on 3 projectors, etc, etc.
Because we have had so much success, and have been at it for 5 years, I try and handicap ourselves a bit. This year we built the car the night before and I limited our build time to 2 hours max. They rarely get paint. Our pack has two derby workshops the two Saturday's before the race where all the parents bring in bandsaws, dremels, scroll saws, drill presses, etc which is a nice touch.
A couple things that have made my son win consistently:
I drill and tap the rear of the car with pipe plugs and use the tungsten weights. Allows us to adjust weight and side to side bias in seconds to make sure the car runs straight and is at the max weight. And I don't have to buy new weights every year.
Our pack allows us to lengthen the wheelbase so we do, car runs straighter.
We also do the one wheel higher trick to minimize friction.
Another trick we do is narrow the width of the front of the car a blade thickness which also allows the car to run straighter.
A few years ago I invested 3-4 hours into the wheels and axles and I reuse them every year. Makes a huge difference.
I built a few cars for the "unlimited" class as well:
A ducted fan car which died on me this year but will be back next year. And a co2 car which is incredibly fast but I won't run it with the kids around as I am scared it will go off track and hurt someone.
