The car only goes as fast as you'll let it go. Even shit cars like Hyundai can go fast.
Last week I seen a guy in a Mazda 3 2.5 I figured... well he has the same SIZE engine as me but with 24 years of 'improvements' he should kick my ass.
He was ahead of me so I let him try to escape and he couldn't. In fact I had to back off.
A few days later I looked up the Mazda 3 to see what the 'stats' are on that thing. 167hp @6000 (my m20 stock 168hp @5800) And I have a few improvements that shouldn't hurt.
Okay... so much for 'new cars are better' I still have more power after 24 years. Next we have weight. Mazda 3... 2969-3108 lb !!! fat as hell. I know I've trimmed about 3-400lbs of niceties from my car so I have that advantage. Too much USELESS garbage in new cars.
Of course you can't compare an e30 to a Mazda 3, that's like comparing nice apples to shitty apples. The e30 was better designed, better made, adjusted for inflation the $30,000 e30 in 87 would be worth $60,606 in 2012.
Okay, okay... I'm slightly off topic.
Advice to the OP: Save your money until he actually accomplishes this idea of his... The big problem I see is you can't swap to a non-stock engine easily in the newer cars. They check these things now when you get emissions.
If you want to play around get an e30.