Marginal cost of operating a modern sedan?

Suppose you own a modern sedan, one of the models that Consumer reports considers highly reliable. Something made by Toyota, Honda, or Hyundai, or the domestic equivalent.

All these vehicles get about 30 mpg. My 90s Honda Accord gets 28 on average, more recent vehicles like the Ford Focus get around 35. So you own the car, and the insurance rate is fixed, so what’s it costing you per additional mile driven to run? Gas prices vary widely, so what I’m really interested in are average maintenance costs. If you drive the vehicle another 100k miles, and gas is $3 a gallon and the car gets 30 mpg, that’s $10,000 of fuel, exactly. If you take the car to a reputable, but non-dealer mechanic when something breaks, and he uses new aftermarket replacement parts, what’s a reasonable guess as to what the bills will add up to be?

The government has figured this out almost exactly for vehicles like military aircraft. Apparently, the fuel costs are barely a drop in the bucket compared to the repair bills.

Almost any job that involves large amounts of driving will reimburse you 56 cents per mile.

http://www.edmunds.com/honda/civic/2013/tco.html

So over 5 years, the maintenance rises until it costs roughly the same as the fuel.