I thought most car owners costs were higher, and so went and tracked down estimates from the americaian automobile association (AAA). The average californian driver driving a new car spends about $7283(*) for the year, however, a 5 year old car was supposed to cost about $4699.
(*) gotta love those extra insignificant figures.
This started when I was looking at report Driven to Spend. I haven't had a chance to do any sanity checks on their report, but they do claim that in most areas transportation is the second biggest cost after shelter. (For New York with it's impressive mass transit system and with only about 46% of the population owning cars, transportation costs fell below that of food.)