Front Wheel Drive versus Rear Wheel Drive
Since the Ford Model T (and actually before) most vehicles manufactured and sold in the United States were rear wheel drive (RWD), that is the engine was typically in the front, the transmission right behind it, with a drive shaft running back to rear axle to drive the rear wheels. The original VW and some other small cars featured rear wheel drive but the engine was behind or above the rear axle, but weíre not going to worry about those.
Front wheel drive (FWD), on the other hand, features the engine under the hood in combination with the transmission (sometimes referred to as the transaxle) that directly delivers power to the front wheels. Despite the impression many people have that the wave of front wheel drive started in earnest with the invasion of the Japanese brands, even those models sold in the US until the mid-1980s were predominantly rear-wheel drive.
Each system has its unique advantages. Front wheel drive makes for a very compact engine compartment, with minimal intrusion into the interior cabin of the vehicle (no large hump for the driveshaft, now just a smaller hump to route exhaust, fuel lines, etc. in a more protected area. Front wheel drive also has certain advantages when the roads get slippery or icy. First, the bulk of the weight is over the front (driving wheels) which assists with traction. The other is that power is being put to the road in the same direction that youíre steering. With a rear-wheel drive vehicle, the front tires might be initiating a turn but the rear wheels are still pointed straight ahead. Excessive application of power at this point could cause a spin.
Rear wheel drive is most commonly found on sports cars and performance sedans. Rear wheel drive is used exclusively in all categories of motorsport where itís allowed. Itís considered the driverís performance as a trained and experienced driver can utilize the power being put down by the rear wheels to help steer the car through turns. Youíll find that rear-wheel drive cars typically feature less interior space than its FWD equivalent, but manufacturers typically install a performance-oriented cockpit with seats that offer more support and extra gauges to better monitor the performance of the vehicle. A rear wheel drive car of the same weight, power, gearing, and tire size and type will accelerate faster than an FWD car, as the weight of the vehicle is transferred off the front wheels and onto the rear wheels to improve traction. FWD cars typically lose traction in these situations.
Which is right for you: Unless youíre a performance enthusiast most drivers are typically more comfortable driving a front-wheel drive car. And for drivers looking for the convenience of an FWD car with a little bit of the performance of an RWD car, well, weíll get to that in a minute.
All Wheel Drive versus Four Wheel Drive
Clearly, the biggest difference between these two systems is that all four wheels are delivering power at one time or another, versus FWD and RWD driving just a single axle each. So immediately we can see that whether itís All Wheel Drive (AWD) or 4WD (Four Wheel Drive) we know immediately that vehicles so equipped would provide improved traction over FWD or RWD vehicles.
Letís tackle 4WD (sometimes referred to as 4X4) first, as it has fewer variations. In a 4WD set-up, each axle (front and rear) is connected to the middle of the vehicle to a transfer case. The transfer case is situated typically at the back end of the transmission. There are typically two settings to a transfer case, but there are some variations. The basic ones are where the front and rear axle can turn independently from one another. This setting is used in dry weather conditions as rounding corners in fully-locked 4WD causes excessive wear in the drive train. The locked setting is for use in muddy, sandy, snowy, or other low-traction situations, and it distributes power equally to all four wheels (it doesnít allow any particular wheel to slip, which would hinder forward progress). Once out of the slippery conditions, the driver would select the unlocked setting on the transfer case and drive on.
Because of the number of differences from manufacturer to manufacturer weíre going to have to speak in some generalities when it comes to AWD. The most common application of AWD is on an SUV or a Crossover that itís based on an FWD platform. Typically the lower-priced versions of that vehicle come equipped with FWD. Instead of a transfer case between the front and rear drive shafts, thereís an open differential. This allows for full-time or part-time engagement of AWD, depending on the vehicle and driver. Some AWD models now feature a system that allows the driver to disconnect the rear wheels when driving on the highway, reducing drag and improving fuel economy. More expensive systems may have a feature that engages and disengages AWD automatically based on the road conditions, as mentioned by sensors and calculated by the computer. In an effort to mimic the all-terrain capabilities of a 4WD system, some AWD system utilizes the vehicleís brakes to control wheel spin. That is, should a wheel start to slip, the brake caliper slows its spinning, mimicking the control of a 4WD system.
How to Select Whatís Right for You and the Way You Drive
For the majority of drivers, a front wheel drive car or crossover is perfectly adequate in most driving conditions. If you live where heavy weather is a concern, you might want to opt for an AWD version of the same or similar vehicle as available. Even if the weather in your area isnít as harsh, but youíd prefer to know that AWD is available is if you need, then the peace of mind is worth the extra cost. As for rear wheel drive and four-wheel drive, those are most often selected by enthusiasts. RWD is popular as the driver can power through a turn unlike a FWD car, while a 4WD is best suited to encounter gravel, muddy, or sandy surfaces, or have to climb or descend steep angles, particularly in limited traction situations.
The sales experts here at Used Car Motor Mall can help walk you through the technologies, allow you to test drive different versions of vehicles equipped with different systems, and help you make the best choice for your driving needs.