In mechanics, the transmission is the set of components that couple the engine and the user, or rather the driver. The transmission parts, roughly composed of clutch, gearbox, transmission shaft, differentials and various drive shafts, allow the transfer of the power released by the engine to the wheels.
After talking, a few articles ago, about four-wheel drive today we focus on the front and rear, highlighting its peculiarities, advantages and disadvantages.
The mechanical differences
Let's start with one of the most important data: unlike the first four wheels, 70% of the cars in circulation are rear-wheel drive. This type of solution is today the most economical, functional and able to guarantee sufficiently high performance. In these cases, the engine is positioned at the front and the front wheels have to cope with the dual task of steering and discharging all the power to the ground.
In this configuration the rear wheels remain substantially free and subject only to the braking system. This is one of the reasons why the front wheels wear out faster and the tires need to be turned, that is swap tires rear and front to each other in order to obtain uniform wear of the entire set of tires.
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La rear-wheel Drive it is generally found on more performing cars, associated in some cases with a positioning of the engine at the rear. This, apart from fundamental driving differences which we will discuss later, allows you to remove the drive shaft. In fact, in front-engined and rear-wheel drive cars, a mechanical connection is required that is able to “transport” the power to the rear: this task is carried out by the propeller shaft.
In this configuration, the front wheels are less stressed and their only task is to divert the vehicle's trajectory through the steering system. The absence of the shaft also entails a considerable advantage in terms of weight reduction: a fundamental characteristic for obtaining maximum performance.
Driving dynamics
In terms of performance and behavior of the car on the road, a lot of things really change; especially if the engine is positioned at the rear. One of the main driving differences between a front-wheel drive and a rear-wheel drive car is the behavior at the limits of adhesion tires; you have surely heard of understeer and oversteer.
Loss of grip is, in general, a condition linked primarily to the driving wheels; as they are forced into motion by the engine. The lack of sufficient friction in a front-wheel drive results in the so-called understeer, easily recoverable by lightening the throttle and steering. Conversely, in a rear-wheel drive the oversteer it tends to close the trajectory and, in some cases, decreasing the power is not enough and it is necessary to resort to counter steering techniques.
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As for ordinary driving dynamics, rear-wheel drive enhances vehicle performance to the fullest thanks to better overall acceleration on dry surfaces and much more precise and effective control; all penalized by a better experience required by the pilot. The difficulties introduced by rear-wheel drive are now amply compensated by a whole series of electronic controls capable of considerably facilitating driving.
The best performance, preferably reserved for the track, can be obtained by deactivating these controls and leaving all the control burdens to the driver's experience. The result is a sporty, lively and fun ride.
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The intermediate solution is represented by the four-wheel drive. This type of configuration is not only typical of SUVs and off-road vehicles but is also widely used on high-performance cars. Some of them, basically rear-wheel drive, are able to transfer part of the power to the front if necessary - take as an example theAlfa Romeo Giulia Quadrifoglio capable of transferring up to 40% of the power to the front. All this penalizes weight and final costs due to the whole set of electronics and differentials more elaborate and expensive.
Rear-wheel drive: the market
Staying low on the budget, there aren't very many rear-wheel drive cars available on the market. We find a somewhat alternative version of the Renault Twingo which, in the 1.0 SCe Wave set-up, presents the rear-wheel drive for less than € 10,000.
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Smart has also revisited the small ones Smart ForTwo e ForFour producing rear-wheel drive configurations. By extending the pace a little, costs and performance are instead a large part of the range BMW e Mercedes-Benz. Then we find the classics Porsche, historically rear-wheel drive, and all that series of high-end cars including Ferrari, Lamborghini, Aston Martin e McLaren.
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Let's not forget about the Japanese, like Mazda e Nissan, and the American muscle cars, which we talked about in a previous Auto for Dummies article. The latter are in fact characterized by a front engine (longitudinal) and a historic and very high power all discharged to the rear.
Conclusions
Front-wheel drive
For 
- Lower costs
- Simple and functional
- Easy response to understeer
Cons 
- Lower overall performance
Rear-wheel Drive
For
- Better performance
- Sporty and fun driving dynamics
Cons
- Little grip on uneven surfaces
- Greater skill required by the driver (especially in oversteer control)
- Higher costs
