Smacktard said:Not quite. Here's a clip from a Forbes article on fuel prices...
http://www.forbes.com/forbes/2005/0509/100.html
If your car ran on unrefined $42-a-barrel crude and got 20 miles per gallon, fuel would cost you a nickel a mile. But add in the cost of turning crude into gasoline and gasoline into miles--i.e., the amortized cost of refinery and car, plus taxes (which pay for the highway, among other things) and insurance--and the mile runs you 30 cents to 50 cents. The IRS lets you expense 37.5 cents per mile for business travel in your own car. The American Automobile Association estimates that it cost an average of 56 cents per mile to drive a new car in 2004. Or to put it another way, driving would be only 15% cheaper, at most, if crude oil were free, or if your car engine delivered 1,000 miles per gallon.
Smacktard, that's somewhat of a poor example for the point I think you are trying to make since it also takes into consideration the cost of taxes, insurance and the car payments to come up with the cost to move the car from point A to point B. Obviously fuel is then only one component of the total cost, so changes in the price at the pump only reflect a portion of all the other costs associated with going from point A to point B. Similarly, if crude oil went down by 50%, you wouldn't expect the CASM of an airliner to drop by 50%.
As your example points out, the price of crude oil only accounts for approximately 15% of the cost to operate a car. The other 85% are insurance, taxes, car payments, maintenance, fuel refinery costs, etc. But let's, for the sake of argument accept that if crude oil were free it would only reduce total costs by 15%. With that assumption, if crude oil were to fall from $50 to $25 per barrel, then that would only amount to a cost savings of 7.5%. That doesn't sound like much, but when your costs are $15B/year, a 7.5% reduction in your operating costs amounts to $1.125B/ year. That's significant.