Yes, interest deduction is a big subsidy, but also roads, cars etc are highly subsidized. I'm on my BB so I can't provide good sources, but if you google subsidies of driving americans etc you will find a lot.
In Europe, they charge very high vehicle and gas tax to make up for the roads and keep people from driving. In the US we allow much less wealthy people to drive. Neither is correct, but we in the US highly subsidize commutes.
IIRC The US Highway system is cash positive. It is true that the US gas-tax is much lower than just about anywhere else. The easiest way to lose the next election in the US is to propose raising the gas-tax.