How to Speak Car Specs

Engine Size/Type
When it comes to engine size/type, don't worry about the details too much—not because it doesn't matter, but because there are surprisingly few categorical assumptions you can make.


How so? Engines are measured by the volume of air it takes to fill their cylinders, which are normally expressed in liters. But it turns out size can mean very little since a very efficient small engine can hugely outperform a much bigger one. Likewise, the camshaft arrangement (OHV, SOHC, DOHC, etc.) can be a non-issue—at least from the driver's seat. OHV engines use the oldest technology, but the best ones can still perform extremely well. The Corvette and Viper spring immediately to mind. The engine's layout (in-line 4, V-6, V-8 or whatever) can tip you off as to the relative operating smoothness you can expect, but not always. More cylinders make for smoother engines, but there are some remarkably smooth four-cylinder engines these days.

Peak HP/Torque
Peak horsepower and peak torque are the two measures that count most in engine performance. You can tell a lot about an engine—and how much you're going to like it—by these figures and the engine rpm associated with them. Peak horsepower represents the maximum amount of work an engine can do. "Work" in this case is sheer pulling power, which may be in the form of acceleration or load pulling. Take special note of the engine rpm that is required to generate that horsepower; if it's a high figure like 5,000 rpm or more, the engine will really need to be spinning fast to do its best work. That means a downshift or two (or even three) will have to happen before the revs are high enough to reach that peak horsepower figure. If you don't like to rev an engine up, you'll never get much of the benefit out of a high horsepower engine that needs a lot of revs.


If you tend to like immediate throttle response with a bare minimum of revs showing on the tachometer, you're a torque person. You not only want to see a big peak torque figure, but you'll want it at the lowest possible engine rpm where it's always accessible.

Transmission
Horsepower and torque figures can tell you a lot, but don't be a slave to them: this is another case where a valued expert opinion or your own thorough test drive can tell you all you really need to know. Besides, these figures are not always honest and accurate, and factors like transmission type and number of gears (more is always better), vehicle weight (lighter equals more performance) and other elements play a big role in the performance a car ultimately delivers.