The engine can be said to be the most important part of a car, and its layout has a significant impact on the performance of the car. For sedans, the layout of the engine can be simply divided into three types: front, center, and rear. At present, most car models on the market use front engine, while center and rear engines are only used in a few performance sports cars.
Of course, according to the placement form of the engine, it can also be divided into horizontal and vertical engines.
front engine 
Front engine, which means the engine is positioned before the front axle. The advantage of a front engine is that it simplifies the structure of the vehicle's transmission and drive axle, especially for the currently dominant front wheel drive models. The engine directly delivers power to the front wheels, eliminating the need for long transmission shafts. This not only reduces power transmission losses, but also greatly reduces the complexity and failure rate of the power transmission mechanism.
In addition, placing the engine in front of the driver can protect the driver from impact in the event of a frontal collision, thereby improving the safety of the vehicle.
Mid engine
Mid mounted engine, which means the engine is located between the front and rear axles of the vehicle, and the cockpit is generally located before or after the engine. It can be said that cars with a mid engine are definitely rear wheel drive or four-wheel drive.
When a car is turning, all parts of the car will move outward due to inertia, and the engine is the heaviest part. Therefore, the force exerted by the engine on the body due to inertia has a crucial impact on the car's steering in the turn. The characteristic of a mid engine is to place the engine with the highest inertia in the vehicle at the center of the body, which can make the weight distribution of the body close to the ideal equilibrium state. Generally speaking, only supercars or sports cars that value driving pleasure use mid engine engines.
Rear engine
Generally speaking, the most authentic rear engine is arranged behind the rear axle, with the most representative being buses. Among the few passenger cars with rear engines, the most representative is the Porsche 911, and of course, the Smart is also a rear engine. The classic models of the Volkswagen Beetle and Fiat 126P were also rear mounted engines.
Horizontal engine
A transverse engine refers to an engine that is parallel to the front axle of a car. Simply put, you stand in front of the car facing the engine. If the engine is placed horizontally in front of you, it is a horizontally positioned engine.
Generally speaking, front wheel drive compact sedans, most mid size sedans, and a few high-end sedans all adopt a transverse engine layout.
Vertical engine
Vertical engine refers to the engine being perpendicular to the front axle of a car. Simply put, you stand in front of the car facing the engine. If the engine is placed vertically in front of you, it is a vertical engine.
Generally speaking, rear wheel drive vehicles use longitudinal engines because power needs to be transmitted to the rear axle. In cases where the transmission distance cannot be shortened, it is necessary to minimize the direction change of power as much as possible. If horizontal placement is used, because the direction of the crankshaft and transmission shaft is perpendicular, the direction needs to be changed first to transmit power through the transmission shaft. However, the direction of the transmission shaft is also perpendicular to the direction of the rear axle, so the rotation direction needs to be changed again at the rear axle, which undoubtedly reduces the efficiency of the transmission system. By using a vertical engine, the crankshaft can be parallel to the transmission shaft, reducing one shift in transmission direction and undoubtedly reducing energy loss.
Inverted engine
"Inverted" is a special arrangement of a transverse engine. The usual arrangement of the exhaust manifold in the front and the intake manifold in the back of a transverse engine is simply "front out and rear in". If the position of the intake and exhaust is reversed, the intake manifold is placed at the front and the exhaust manifold is placed at the rear, becoming "front out and rear out", it is called "inverted". Only horizontally mounted engines have the concept of "front and back", while vertically mounted engines have intake and exhaust manifolds at the left and right ends, and there is no significant difference when swapped, so there is no such concept.