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One of my strong interests is in cars and driving. I like to learn how cars work by studying them and getting my hands dirty working on them. I like to study the art of driving too, since it is a daily application of Physics. Again, I like to be hands-on and there are safe places to explore the art of precision driving in the form of autocrossing and rallycrossing. My car daily driver is a 1998 Subaru Legacy wagon, which I got in December 2002, when the 1987 Chevrolet Cavalier became the victim of crazy Forsyth traffic/driving. I got everything I wanted - 5-speed manual (faster in Subarus than the autobox), AWD, and a wagon with plenty of room. The 1993 Cadillac Fleetwood is the not-as-practical backup car - though it brings a surprising amount of driving pleasure in addition to catering towards comfort-oriented interests. So here's the stuff that matters to me when it comes to the car I drive: Handling. I prefer the handling of cars as opposed to SUVs and vans. I think the point at which a vehicle is too tall and has too high a center of gravity for me is somewhere under the 1.1:1 height-to-track ratio. I really enjoy all the directions of driving - not just forward propulsion, but also good handling and braking. Most car clubs will not allow you to autocross or rallycross vehicles with too high a center of gravity for safety reasons.
Space. There are several cars out there that can be acquired in either sedan or wagon form. As a daily driver, I'm definitely all about the wagon. It usually doesn't weigh that much more (only about 100 pounds), and is the same length and width as the sedan version. Having a hatch instead of a sedan trunk makes that space behind the back seat so much more useful. Furthermore, many sedan's now don't have the fold-down rear seats anymore. Most wagons will swallow more stuff than these cute-ute SUVs out now. The reality is, there are some times when it's nice to have the option of lots of room inside a car, and when you can have that option all the time, and still have a vehicle that handles and performs like a good sedan, I'm all over it. Traction - what handling is all about. The drivetrain layout of a car (FWD, RWD, AWD) determines what happens to the power the engine delivers in a car under traction-limited situations. Most people associated limited traction with inclement weather such as rain or snow, or even off-road situations. However, when a vehicle is turning, braking, or accelerating aggressively on dry pavement, it is also experiencing a traction-limited situation. Therefore, the potential traction advantages offered by AWD can benefit a car under all situations. In a 2WD vehicle, if you exceed the traction available to those 2 tires, one or both of the tires start to spin and slide relative to the pavement. This happens frequently to people when they're driving on wet surfaces, however, it can also happen if you are negotiating an aggressive turn, and the tires are using up most of the traction to turn the car. For example, if a particular turn at a particular speed is using up 90% of the front tires' traction, and 70% of the rear tires' traction, and the car is FWD, there is really only 10% as much traction available for forward propulsion as there would be if the car was standing still. Therefore, even small applications of the throttle can cause the front tires to spin. AWD, however, offers the potential of utilizing whatever traction is left of all four wheels, instead of just the two that are driven, so there can be more forward propulsion than a 2WD car, therefore allowing the car to go faster, whether the situation be a wet road, snow, or an aggressive turn.
A good AWD system not only provides extra traction in low-speed, low-traction situations (like light off-roading), which 4x4 trucks and SUVs have been doing for years, but is always engaged and and working to enhance driving dynamics under all situations, including high-speed cornering on the racetrack. This is where most AWD systems in SUVs stop - even in their promotional literature they advertise that after 35 mph or some arbitrary speed the AWD disengages and it becomes a FWD-only vehicle. AWD systems generally rely on differentials (up to 3 on an AWD car) to distribute power between 4 wheels, since a differential allows tires to move at different speeds (which inherently happens when you take a turn) while transmitting power. The best differentials rely on mechanical limited-slip mechanisms with electronic enhacements to optimize traction in all situations. The optimal distribution of power to the wheels while mudding is obviously very different than when you are taking a high-speed turn on dry pavement. This is why you find steering input sensors, yaw sensors, and lateral g-force sensors in expensive German vehicles (AWD or not) - good traction control is many steps beyond reading wheel speeds and applying brake power to the slipping wheel, or cutting the throttle and taking control away from the driver. Here is my personal ranking of AWD systems and their ability to enhance vehicle dynamics on all situations:
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Cars: Driving | Subaru | Cadillac | Chevrolet
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