Why Weight Is More Critical To a Car Than Horsepower

Horsepower is important for some things, but in the real world, weight and torque delivery is what you should care about most.

When a new car debuts, one of the most important numbers people seem to care about is the horsepower. It makes sense, right? On the surface, it seems like an easy, singular number to compare against rivals and give an idea of how capable a car is. In reality, that horsepower number isn't nearly as relevant as a car's weight.

In his latest video, Road & Track contributor Jason Fenske of Engineering Explained breaks down how horsepower and weight affect each other, and why a car's curb weight is the most important factor in determining performance and fun.

The thing to keep in mind is that horsepower is heavy. That means the more power your car has, the heavier it will become. Why? Well if you want more power, you need a bigger engine, beefier axles and driveshafts, stronger transmissions, and bigger brakes to handle the extra shove. That stuff starts to add up, and before you know it, your car weighs two tons. Not great!

The best example Fenske gives uses downforce to explain things. Let's say you have a 4000-pound car that makes 2000 pounds of downforce. That means it can generate 1.5 gs of lateral acceleration in a corner, which is pretty good. Now, let's say that same car is 2000 pounds, and generates the same 2000 pounds of downforce. That car can generate a full 2.0 gs of lateral acceleration. That means this theoretical car can go a lot quicker around a track without any change to the power.

Fenske makes a bunch of other good points in the video as well. He explains that while horsepower is important for top speed, it's torque curve and instant power delivery that matter in the real world. How often do you accelerate to 60 mph versus go on top speed runs? It's the low-end stuff you feel most of the time, and that has little to do with that horsepower number—it's all weight and power delivery. So next time you look at a stat sheet, maybe pay a bit more attention to that curb weight number.

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