Why have horsepower numbers changed so much over the last 30 years?

Dear Car Talk

Dear Car Talk | Nov 01, 1995

Dear Tom and Ray:

Back 30 years ago, the average V8 had 300 horsepower ratings. My '68 AMC Javelin, which had a "small" V8 had 280 horsepower. In the 90s, cars with anything over 200 hp are considered high performance. 200 hp back in the 60s would be considered puny. Have the specifications changed, or is there some other explanation for this?

RAY: Gee, Larry. You wouldn't think 200 horses was nothin' if you were the stable boy... and had to clean up after them!

TOM: Actually, it's a good question, Larry. Horsepower is horsepower. And you're right that cars today DO have less of it. But they don't need as much.

RAY: Because they weigh so much less, "performance" cars of today are just as fast as the cars you romanticize, even though they have less horsepower.

TOM: The main factor in acceleration is the "power to weight" ratio. Lets say your '68 AMC Javelin had 280 horsepower and weighed 4,200 pounds. That would mean there was one horsepower for every 15 pounds of car.

RAY: Now take the 1996 Nissan 300ZX. The least powerful engine in that car--the six cylinder, non-turbo--produces 220 horsepower in a car that weighs about 3,300 pounds. That means the 300ZX has one horsepower for every, guess what? 15 pounds of car!

TOM: If the car weighs less, it doesn't need as much power to make it go fast. And most cars today weigh between 2,000 and 3,500 pounds; whereas in the 60s, the average weight was probably between 3,500 and 5,000 pounds. So today, through the wonders of modern technology and weight reduction, idiots like my brother can go fast enough to kill themselves using smaller, lighter, cleaner, more efficient engines which produce less horsepower.

RAY: This is what we call "progress," Larry.

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