When you add together an average car payment (or payment to your own personal 'car fund'), insurance (I'm in Michigan, so because of our stupid no-fault unlimited PIP it's close to $200/month by itself), gas (15k miles, 25 mpg, $2.50 = $1500), oil/maintenance, the average eventually comes out to around $10k/year.

Personally, I'm driving an old vehicle and the total annual cost has been about half that, but on the average people are spending that much.