In automotive design, a FR, or front-engine, rear-wheel-drive layout is one where the engine is located at the front of the vehicle and driven wheels are located at the rear via a drive shaft. This was the traditional automobile layout for most of the 20th century. Modern designs commonly use the front-engine, front-wheel-drive layout (FF). It is also used in high-floor buses and school buses.
In automotive design, a front mid-engine, rear-wheel-drive layout (FMR) is one that places the engine in the front, with the rear wheels of vehicle being driven. In contrast to the front-engine, rear-wheel-drive layout (FR), the engine is pushed back far enough that its center of mass is to the rear of the front axle. This aids in weight distribution and reduces the moment of inertia, improving the vehicle's handling. The mechanical layout of an FMR is substantially the same as an FR car. Some models of the same vehicle can be classified as either FR or FMR depending on the length of the installed engine (e.g. 4-cylinder vs. 6-cylinder) and its centre of mass in relation to the front axle.