Here's how some cars compare in power to weight and overall performance.

When researching performance figures of new cars, you may have come across the statistic for power to weight ratio. What is power to weight ratio? Basically, the measure of what makes a small engine car powerful and a big-engine beast docile.

You take a vehicle’s horsepower and divide it by its curb weight. That gives you the power-to-weight ratio, which is represented as horsepower to 10 pounds. The higher the number, the better your car is going to be in terms of performance. In effect, look for cars with horsepowers to weight above one. It’s explained below.

The website measurespeed.com has an easy-to-use power to weight calculator. Simply plug in a vehicle’s curb weight and its horsepower and it gives you the number. For my purposes, I researched two cars: the 2015 Alfa Romeo 4C and the 2015 Bentley Continental GTC. Here are the results.

Alfa Romeo 4C

  • 237 horsepower (four-cylinder)
  • 2,487 curb weight
  • .95 hp to 10 lbs. power-to-weight ratio

Bentley Continental GTC

  • 500 horsepower (V8)
  • 5,478 curb weight
  • .91 hp to 10 lbs. power-to-weight ratio

By that measure alone, we can see that the Alfa Romeo 4C is the better car in terms of power to weight. But neither car meets the golden standard of one horsepower to 10 pounds. Start to reach that number and you’re getting into some truly sporty cars. Who makes that list? At 1.58 horsepower to 10 pounds, the 2015 Dodge Challenger Hellcat finds itself as probably one of the top Americans. Overall, it’s going to be hard to beat the 2016 McLaren 675 LT with its power to weight ratio of 2.29 horsepower to 10 pounds.

Is power to weight the end-all and be-all of performance? Not necessarily because it doesn’t reflect a car’s handling or braking ability. But if you are looking to narrow down your choices, it’s not a bad place to start. Plus, it makes you sound more knowledgeable to your friends if you can quote your car’s power to weight ratio. I won’t be sharing the number for my 2008 Mazda Mazda5 any time soon but I did drive a 2015 Lamborghini Huracan (shown above) recently. Its power to weight ratio is 1.95 horsepower to 10 pounds.

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