the original article was obviously biased quite a bit towards all wheel drive, and most of his facts were correct.
he omitted a very important con of all wheel drive though; the extra weight an all wheel drive carries is not just static mass. an all wheel drive car adds more weight to the gearbox, a center differential, a big driveshaft, a rear differential, two more halfshafts, two wheels, two brake rotors, and two tires to the mass turned by the engine. thats a lot of damn mass, whether you like it or not. yes, it helps transfer the power to the road, but at higher speeds (say, 60mph and above) our cars cannot accelerate enough to keep the weight transferred to the back of the car. the nose falls back down.
front wheel drive is horrible from a stop. front wheel drive is less than desirable in turning as well. there are some cases, though, where the relatively light rotational mass of a fwd drivetrain is optimum compared to an all wheel drive platform.
lets take a hypothetical situation in to consideration. two cars line up at a track: 275 crank horsepower gst, and 275 crank horsepower gsx. the light drops, and both cars are off. the gsx pulls a 1.9 second 60', and the gst wheel hops out a 2.3 second 60'. the gsx is obviously ahead at 60 feet by a pretty large margin already. by the 1/8th mile, the cars cannot accelerate fast enough to keep the weight transferred back. the gsx crosses at 80mph at 9.2 seconds, and the gst crosses at 75mph at 9.7 seconds. the gst is still trapping lower speeds at greater time intrevals than the gsx; infact, the gst has lost another tenth of a second on the gsx. the quarter mile comes. gsx clicks off a 13.5 at 102.5mph. most of the weight is divided up equally on the tires by the last 1/8 mile of the race on both cars. the gsx's engine still has to turn all the extra mass, though. the gst clicks off a 13.8 at 110mph. now the gst gains back 2/10 of a second on the gsx, and although clocked 0.2 seconds later, has 7.5mph more than the gsx. 3/8 mile comes. the gst is dead even with the gsx at say 18.0 seconds for both. the gsx traps 125mph, and the gst traps 140. the driveline is starting to hurt the gsx. by a half mile, the gst has pulled the gsx in and passed it, and is travelling faster than it.
drivetrain loss, folks. in an 1/8th mile, having all wheel drive outweighs it. in a 1/4 mile, having all wheel drive outweighs it still. in a 1/2 mile, the lighter drivetrain will come back to win.
rear wheel drive is somewhere inbetween those. rear wheel drive still has a driveshaft, rear diff, rear brakes/wheels/tires, but drops the fronts, extra gearbox weight, and center diff to put the power where it will work best under heavy acceleration: rear wheels. why not have the best of both worlds, though? stick an engine in the back of a car with the same light drivetrain of a fwd car. midship mounted engines will whoop as much ass from a roll, and still have grip from a stop. the only problem with this is that there are very few affordable mr cars. vw bug, mr2, fiero, boxster are all come to mind. thats about it. apart from that, trunkspace is eliminated, as well as rear seats. those are two points that sell cars in this day and age, thus the absence of mr cars.
rougly,
awd: 30% drivetrain loss
rwd: 25% drivetrain loss
fwd: 15% drivetrain loss
mrwd: 15% drivetrain loss
so basically, yes fwd cars get raped from a stop and to a 1/4 mile. anything past there, and the fwd will reel them in. any point past 60mph or so where the engine can't push the car back enough to lose traction in the front, the fwd will go faster.
he omitted a very important con of all wheel drive though; the extra weight an all wheel drive carries is not just static mass. an all wheel drive car adds more weight to the gearbox, a center differential, a big driveshaft, a rear differential, two more halfshafts, two wheels, two brake rotors, and two tires to the mass turned by the engine. thats a lot of damn mass, whether you like it or not. yes, it helps transfer the power to the road, but at higher speeds (say, 60mph and above) our cars cannot accelerate enough to keep the weight transferred to the back of the car. the nose falls back down.
front wheel drive is horrible from a stop. front wheel drive is less than desirable in turning as well. there are some cases, though, where the relatively light rotational mass of a fwd drivetrain is optimum compared to an all wheel drive platform.
lets take a hypothetical situation in to consideration. two cars line up at a track: 275 crank horsepower gst, and 275 crank horsepower gsx. the light drops, and both cars are off. the gsx pulls a 1.9 second 60', and the gst wheel hops out a 2.3 second 60'. the gsx is obviously ahead at 60 feet by a pretty large margin already. by the 1/8th mile, the cars cannot accelerate fast enough to keep the weight transferred back. the gsx crosses at 80mph at 9.2 seconds, and the gst crosses at 75mph at 9.7 seconds. the gst is still trapping lower speeds at greater time intrevals than the gsx; infact, the gst has lost another tenth of a second on the gsx. the quarter mile comes. gsx clicks off a 13.5 at 102.5mph. most of the weight is divided up equally on the tires by the last 1/8 mile of the race on both cars. the gsx's engine still has to turn all the extra mass, though. the gst clicks off a 13.8 at 110mph. now the gst gains back 2/10 of a second on the gsx, and although clocked 0.2 seconds later, has 7.5mph more than the gsx. 3/8 mile comes. the gst is dead even with the gsx at say 18.0 seconds for both. the gsx traps 125mph, and the gst traps 140. the driveline is starting to hurt the gsx. by a half mile, the gst has pulled the gsx in and passed it, and is travelling faster than it.
drivetrain loss, folks. in an 1/8th mile, having all wheel drive outweighs it. in a 1/4 mile, having all wheel drive outweighs it still. in a 1/2 mile, the lighter drivetrain will come back to win.
rear wheel drive is somewhere inbetween those. rear wheel drive still has a driveshaft, rear diff, rear brakes/wheels/tires, but drops the fronts, extra gearbox weight, and center diff to put the power where it will work best under heavy acceleration: rear wheels. why not have the best of both worlds, though? stick an engine in the back of a car with the same light drivetrain of a fwd car. midship mounted engines will whoop as much ass from a roll, and still have grip from a stop. the only problem with this is that there are very few affordable mr cars. vw bug, mr2, fiero, boxster are all come to mind. thats about it. apart from that, trunkspace is eliminated, as well as rear seats. those are two points that sell cars in this day and age, thus the absence of mr cars.
rougly,
awd: 30% drivetrain loss
rwd: 25% drivetrain loss
fwd: 15% drivetrain loss
mrwd: 15% drivetrain loss
so basically, yes fwd cars get raped from a stop and to a 1/4 mile. anything past there, and the fwd will reel them in. any point past 60mph or so where the engine can't push the car back enough to lose traction in the front, the fwd will go faster.
