This single ratio represents how fast a car is, in very simplified theory. The higher the number, the faster the car is. To get it, power is divided by weight. The more power - the faster. On the contrary, more curb weight will mean the car is harder to accelerate.

Bigger engines use shapes like V6 and V8. Smaller engines are usually I4. The number refers to cylinders and the letter refers to shape of their arrangement. Rarer designs include boxer and rotary engines.

Power, that is what its all about. This is the basic measurement for car engines. The higher, the faster usually. Don't forget that the heavier the car, the more power it requires.

The compression ratio is one of many ways to gauge engine design. The higher the ratio, the better designed the engine is since more mechanical energy can be extracted from it. In other words, more of the explosion turns into power sent to the wheels, which is good efficiency.

These are the dimensions of individual cylinders. Stroke is the length and bore is the area of the cylinder's footprint. Long stroke engines develop more torque, making it great off-the-line. However, shorter stroke allows the engine to spin faster and create more top end power, making them great for highway or racing.

Engine displacement is the size of the engine, except on the inside. It is the internal volume of all cylinders. The larger these chambers are, the more torque can be developed. This is why larger engines have so much pep from a standing start.

Valvetrain is the part of your engine that controls how fuel and air enters and exists the cylinders. SOHC is the cheap design. DOHC is a the more expensive design often used in performance vehicles. The number represents the total number of valves. The more - the better, performance-wise.

How well is the engine designed? One way to evaluate this is to ask how much power the engine gets for its size. The higher the number, the better engineered the unit it. Higher values allow to have both high power and reasonable economy.

Distance between the centers of the axles. This is the length if you were to stretch the tape measure from the center of the front wheel and run it back to the center of the rear wheel.

This tells you how many miles you can, on average, travel in this car through city on a single gallon of gas. Keep in mind that these numbers are an approximation from the EPA and shouldn't be trusted. There are much better resources for what to actually expect: FuelEconomy.gov and Fuelly.com.

Number of miles, on average, this car travels on highway on a single gallon of gas. This one really varies and depends on how you drive. Don't forget to always check FuelEconomy.gov and Fuelly.com. In fact, why not join Fuelly?