That's what I do - the last time that I paid cash for a new car was in 1985 (interest was 15% at that time). Since then I have financed our cars 100% - ie, zero down, 60 months of payments. I get the results that Dave suggests - except that my average return is about 11%/yr, not 12..
As for junker, used car, new car - that's a separate debate. As long as you can get inexpensive rates (<5%), you will do better by 100% financing. And leave your own money invested at 11%/yr.
The people Paul are saying should get car loans are the ones with no money. They're not keeping the money invested at 12% or 11%. They're just going into debt.
AND those people aren’t likely to qualify for .9% financing or anywhere close to it, so the mythical $200 payment is just that for this population.