Power And Grip Scale
Published: April 3, 2017
Throughout the site I use terms like "low power" and "high grip" cars. Here I will define what I mean by them.
While some cars are clearly "low power" (a full size car with less than 100 hp is clearly a low power one) or "high grip" (a Formula 1 car is arguably a high grip vehicle), cars present a continuous spectrum of capabilities and there are plenty of vehicles that cannot be clearly bucketed into any of the categories I am about to present. In these cases a compromise between the closest matching categories is typically how the car would behave.
Although the term "power scale" does not mention weight, the definition takes vehicle weight into account and I would break the cars down as follows:
- Low power: 15 lbs/hp or more, meaning under 150 hp at 2500 lbs, under 200 hp at 3000 lbs and under 250 hp at 3500 lbs.
- High power: 10 lbs/hp or less, meaning over 250 hp at 2500 lbs, over 300 hp at 3000 lbs and over 350 hp at 3500 lbs.
- Medium power: between 10 and 15 lbs/hp.
Some typical examples:
- Miata: 115-140 hp at 2300-2500 lbs, low power.
- BMW E30: 170 hp at 2700 lbs, low power.
- BMW E36 M3: 250 hp at 3200 lbs, medium power.
- C5 Corvette: 350 hp at 3500 lbs, high power but barely.
- C5 Corvette Z06: 400 hp at 3500 lbs, high power.
- C6 Corvette Z06: 500 hp at 3500 lbs, high power.
A dedicated track car with gutted interior and street amenities like air conditioning deleted generally weighs 100-200 lbs less than the corresponding street car.
Curb weight as quoted in automotive publications does not incude fuel and driver, which add another 200-250 lbs to the car's weight. When talking about car weights on road courses we generally refer to the weight of the car as it is driving on track, including driver and fuel. This weight is sometimes referred to as "race weight".
The grip scale in general looks like this:
- Low grip: all-season tires.
- Medium grip: high or extreme performance summer tires.
- High grip: DOT R compound tires and non-DOT race tires.
However, weight affects grip too. A heavier car generally works the tires harder than a lighter car. A Miata on extreme performance summer tires can potentially drive high grip lines, whereas something like a Challenger Hellcat on the same tires may feel like a low grip car.