Decisions are made at the margin for nearly every large purchase. 10k has been enough for plenty of people to pass on a house. Plus, as several people in this thread have noted, the distaste if paying $5k in tax is larger than in paying an extra $5k for a more expensive vehicle.
Whatever, it's clear that expensive cars are a societal evil that must be reduced, if not eliminated entirely. We have a variety of sin taxes in this country that we feel are totally reasonable. Being rich is about as socially acceptable as smoking these days. It should be done out of sight ideally.