As a finance person...I am iffy about the whole deal. You seem to talk a good game or whatever...but I am not understanding paying cash from a purely financial standpoint. First off, what type of credit do you have...if it is good enough you can get some very low apr. You can get some BBB rated bonds that pay in the high 8s (GM for instance)...You pay 4%, recieve 8% you gain 4% (more to it than this, but simplified) If not, perhaps but the car in their name and add you as a co-signer. Some places may not like this but explain that you may be trying to build your credit, but at a low rate. Few places may do this for you.
You ever listen to Dave Ramsey or something. Well, he is a fool. He knows nothing of financial leverage. He never suggests how one could use debt to improve situations. Why do all fortune 500 companies (besides saab, I believe) use debt as a mechanism to improve themselves. Why can't people? I still don't understand his methodology.
Lastly...if you are a person who pays cash only, you should look into a cf (certified used) they are usually 2-3 years old (which means they have already took a bulk of the depreciation as a percent of complete depreication) furthermore they come with warranties for a several years.
I wouldn't buy a car under 6 years old but wouldn't drive it more than 2 years.
Unless you are one of those types that like buying a new car, then there a certain intrinsic value to that, but no monetary value. and I can respect that.