It's worse than that, if you're on a world on your own your top 10 cars becomes copies of your best car. You destroy diversity even quicker with fewer players!
At least with lots of players, as pubnub said, some of those identically named cars were actually different generations and different cars, but were cousins or otherwise related from a common ancester.
One recommendation would be to incorporate any mutations into the ID, so if it started f0660f and mutated it would be f0660f0b or something, to track parentage (And in fact it would be cool if crossovers were tracked in the ID too, a bit like the Russian patronym or spanish matronym)
Updates have been made and now we are at 2.52 for improved Champion Generation.
What did you do? Now most champions don't actually work. They get stuck at the start.
The last time I looked at genetics, I remember a method that selected the top n genes and added a number of completely random (no crossover) genes to fill the population of the next generation. Would it be enough to add a number of completely random seeds each run?
And right now the setup appears to be such that you'll end up destroying all diversity from the gene pool as soon as you have more than a few users.