Understanding the Drive Layouts
The drive layout is the arrangement of the engine, transmission,
and driven axles. The types of drive layouts are Front engine
Front wheel drive (FF/ FWD), Front engine Rear wheel drive
(FR/RWD), Mid engine Rear wheel drive(MR), Rear engine Rear
wheel drive(RR), Four wheel drive (4WD or 4x4) and the All Wheel
Drive(AWD). Each of these layouts has their own performance,
advantages and disadvantages.
Front engine Front wheel drive (FF/FWD) - The Engine and the two
driven axles are placed in front, where the power from the
engine is transferred straight to the front wheels. This layout
increases the interior space especially in small cars because
there is no central tunnel needed for the driveshaft. FF layout
has advantage when it comes on low grip surfaces, and its
tendency to understeer reduces the risk of losing control. The
disadvantage is the load placed on the front tires. The front
tires must transfer all acceleration, steering, cornering, and
braking forces to the road. This kind of tasks gives a lot of
stress in front tires which may lead to wear and tear, while the
rear tires have very little load on them.
Front engine Rear wheel drive (FR/ RWD) - This is the complement
of FF layout, where the engine is placed longitudinally at the
front but the two driven axles are placed at the rear connected
through the driveshaft. With this kind of layout, installation
of more powerful engine such as V8, V10 and V12 is not a
problem. Since the FR has a driveshaft, central tunnel is
present in this layout a little interior space is sacrificed.
All of the disadvantages of the FF layout are the advantages of
FR layout. Mid Engine Rear wheel drive (MR) - The drive layout
that consumes a lot of interior space of the car especially the
seating capacity, the engine is placed in the middle of the
chassis and the driven axles are at the rear. Although it has
more weight at the rear, entering a corner makes it more
difficult because the front tires have less traction resulting
to understeer and since the rear is heavy, the car tends to
oversteer when exiting a corner. This kind of layout is commonly
used in racing cars and sports cars because of weight
distribution focused in the center of the car.
Rear engine Rear wheel drive (RR) - This layout places both
engine and the driven axle at the rear of the vehicle, even
though the rear wheels benefit from the additional grip due to
the added weight given by the engine, the front wheels still
need grip in order to steer the car effectively. That's why RR
layout car can also be prone to understeer. Four Wheel Drive
(4WD or 4X4) / All Wheel Drive (AWD) - It is a term usually used
to describe a car where the four wheels receive power from the
engine simultaneously. This can be found in an off-road vehicle.
A well distributed power to the four wheels improves the grip of
the vehicle. The terms 4WD and 4X4 are used in jeeps and other
off-road vehicles that require the driver to switch from 2WD
used in street driving (two wheel drive) to 4WD to improve the
grip depending on the road condition like mud, snow, etc. and it
has a high and low gear selection. The AWD term was invented to
identify the vehicle capable of driving all the wheels on any
road condition without selecting high and low gear selection
because the power is distributed on all the wheels. Unlike the
4WD with gear selection, you don't have to select the
appropriate gear to match the road condition. Most of the modern
cars use AWD system for more traction and better handling.