DIFFERENT TYPES OF LAYOUT IN AUTOMOBILES

1.)Front engine front wheel drive 

Front-wheel drive is the most common form of engine/transmission layout used in modern passenger cars, where the engine drives the
front wheels only.In this layout a front mounted engine-clutch-gear box unit drives a beam type rear axle suspended on leaf sprints through a propeller shaft with two universal joints.  Most front wheel drive vehicles today feature transverse engine mounting, though many in prior decades were positioned longitudinally instead.

Advantages:-

•  Balanced weight distribution between the front and the rear wheels.
• Easy front wheel steering.
• Behind the rear seats, large luggage space is available.
•  Accessibility to various components like engine, gearbox and rear axle is better in  comparison to other layouts. The control linkages-accelerator, choke, clutch and gearbox are short and simple.
• Full benefits of the natural air stream created by vehicle’s movement is taken by the forward radiator resulting in reduced power losses from a large fan.
• Small length of the propeller shaft permits the angularity of the universal joints to be small and easily provided by simple types.

2.)Rear engine rear wheel drive

Rear-engine, Rear-wheel-drive layout places both the engine and drive wheels at the rear of the vehicle.It is shown in figure below

Advantages:-

• Better road adhesion preferably on steep hills and while accelerating with increased weight on the driving wheels.
• Generally a proportional part of weight of the car is transferred to the front wheels while braking. Therefore, due to the firm road surface contact maintained by rear engined car results in assistance to stopping of the vehicle.
• In this arrangement, front wheels are only for steering purposes.
• The necessaity of the propeller shaft is altogether eliminated due to the combination of engine, gear box and final drive. This also requires only one common oil sump.
• Good visibility and stream lining is provided by proper design of vehicle front.

3.)All wheel drive

An AWD vehicle (short for All-wheel drive vehicle) is one with a powertrain capable of providing power to all its wheels, whether full-time or on-demand.It appears in everything from supercars with out-of-this-world performance like the Audi R8 to family crossovers and SUVs like the Volvo XC90.

Advantages:-

• As compared to rear wheel driven car, there is a faster and safer travelling due to good road holding on curves.
• Gives sportier handling and traction to a broader range of cars.
• A lower flat floor lines is provided due to dispensing with the propeller shaft resulting in lowering of centre of gravity.
• The engine, clutch, gear box and final drive are combined similar to the rear engine car. This provides a more comfortable drive due to final drive spring. 
• Good road adhesion is obtained due to a large part of the vehicle’s weight being carried on the driving wheels under normal conditions.