Had it been a Screaming Yellow instead of Oxford White I would go for it.

Go with the Red Fire '05 GT.

 

In two months, that '04 will be a year old (fiscal year). Take that into consideration on your price.

Otherwise, your personal tastes as technically, both will be brand new cars with similar specs.

 

Bzzzt!

Listen, when I bought my 1966 Mustang 2+2, it was barely 15 years old, and it was ALREADY a "classic". They made just over 100K of the fastbacks in 1965-6, but they produced over 1.1Million mustangs in total those 2 years combined. In 10 years they were recognized as classics, and were appreciating.

Name one mass produced car from 1990 that is a classic, appreciating in value.

The reason you think that 30 years is some magic number is that there have been ZERO high volume, mass produced cars in 30 years that are considered "classics". None of the cars from that era that made over 50K copies a year are appreciating. None that I can think of.

Classic mustangs weren't even a good investment as-new. Do some basic math, use an online internet-based inflation calculator if you must.

A mustang coupe in 1965 cost under $3000 for a V8. If you put it in a garage, rarely drove it, kept it in near perfect shape, you could sell it for $20K (we're talking coupe, not fastback or convertible).

If you average for inflation, that $3000 would be $22K in todays dollars. Pretty much a wash with the car.

If you invested it in a Dow Jones Industrial mix of stock, it would be worth about $33K.

Don't buy a massed produced car as an investment. You are delusional if you think you'll make money.

Buy it, drive it, enjoy it. Pamper it or beat it, it's your car. Just don't expect to make any money on it.