I bet if you started off with a solid mid/high 11 sec car it would be more like $10,000 for every half second and then maybe $10,000 for every quarter sec at a certain point.
11.50+: start
10.99: $10,000
10.49: $10,000 more
9.99: $10,000 more
9.49: $10,000 more
9.24: $10,000 more
8.99...