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Ask Joanne

Horsepower vs. torque: what you need to know Add to ...

The dealer is trying to get me to upgrade to a higher trim level because it has more "horsepower." Is this important or should I stick with the base model, which does have less horsepower but almost the same torque? - Erica in Victoria

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Whatever the goods may be, when someone is trying to up-sell, you're right to ask yourself whether you really need it.

The answer really depends on what you are buying the car for, and therefore what kind of driving you will mainly be doing. Will you be spending your drive time cruising long distances on the highway, towing a boat to the lake, or nipping about in the city?

There's an old quote in racing that horsepower impresses your friends, but it's the torque that will win you the race.

"Horsepower, in physics or engineering terms, is a measure of work, and work is defined as moving something with some force in a certain amount of time. Torque is a force, and can be briefly described as what force it takes to turn an axle or a rod. Horsepower and torque are related based on the speed of the engine," says Gary Pollak, program manager for ground vehicle standards with the Society of Automotive Engineers (SAE) International.

"In essence some vehicles are designed to have higher horsepower, but the higher up that horsepower is on a horsepower curve may mean that you can't take advantage of it until you're at a very high rpm. So an engine could be very powerful but it could take a long time to get up to that power," says Pollak.

"It's a personal preference. A higher torque rating probably would feel like a more powerful engine at the very low speeds, driving around town, etc. Sometimes manufacturers try to tweak the smaller engine cars to provide that high torque upfront so people feel like the car is responsive, and feel they have what they need to get from one stoplight to the next. But if you had that same car out on the highway, as you get up to speed then it tops out and you might not have the speed to accelerate quickly," says Pollak.

"Usually everyone is looking for higher power, not torque. Generally when you increase the horsepower though, you increase the torque, but not always; different manufacturers build their engines in different ways, so you might end up buying two engines which have the same torque but different power characteristics," says Dan Centea, chair of automotive and vehicle technology for the McMaster-Mohawk Bachelor of Technology Program. "Power and speed are related, but unless you're a race car driver, increased speeds are just going to get you in trouble with the law."

A larger engine is often part of a larger trim package designed to increase profit for the manufacturer. In fact, if you want that sun roof or navigation system or other optional extras, you may not be able to get them without moving up to a bigger motor.

Remember, though, that with a bigger engine, you're likely to be burning more fuel. There will also probably be an increased maintenance cost, especially on a turbocharged or supercharged engine.

Don't be swayed by a shiny sales pitch.

Evaluate your options based on your driving needs and make sure you take both models out for a spin to test which combination works. If you find the base model is sufficient, save yourself some money and leave the extra horsepower to the Indy 500.

E-Mail Ask Joanne at globedrive@globeandmail.com


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