Reply #1: Tweak the hell out of them. [View All]

[flvegan]

Actually, cars are generally getting heavier these days, what with all the safety and convenience equipment. While carbon fiber and aluminum is being used more on high end cars, something like the Civic won't come stock with anything like that anytime soon.

I know one of the big parts of the Si engine upgrade is upping the internals (compression is a couple points higher, IIRC) and tweaking spark, electrics, etc. Having an 8k rpm redline doesn't hurt performance, either (not that it makes horsepower). So much of it is computer related these days. Air flow, spark and fuel management, timing, and so on combined with a well-managed and thought out engine and exhaust.

When I was in high school I had a Corvette. Naturally it came with a 350 cubic inch V8, but stock had 180 or 190 horsepower. MIGHT have gotten 15 mpg. Today, I have a Mazdaspeed 3. 2.3 liter 4 cyl, factory turbocharged, 263 horsepower. I get well over 20 mpg while driving like a maniac.

We've come a long way.