I am not sure what the perceived wisdom is when concerned with FWD and RWD, but I can only comment how I find it. I personally hate torque steer, so that is pretty much most FWD diesel cars. I have a loan car at the moment which has a 2.2d 154 bhp engine in it and it pulls ferociously when the torque steer kicks in. It also has optional 4wd (it is a Mitsu Outlander).
It did get me thinking as to why, when a car has switchable 4wd, does the 2wd bit always be FWD. I know that on conventional 2wd cars FWD is both cheaper and saves having a drive shaft going down the middle of the car, but as the rear wheels can be driven wouldn't it be better to be RWD? I presume that it comes down to cost again, and no doubt space. Perhaps someone more informed could explain.
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Perhaps because FWD (in 2WD mode) is better at maintaining traction - especially in the likely scenarios that they'll be used. Isn't one of the downsides of RWD cars, their inherently more tricky & edgy traction characteristics in slippy, muddy, icy conditions? Something I've noticed anyway, having had FWD, RWD & 'intelligent' mode 2/4WD vehicles in the past few years.
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In older LandRovers RWD was the norm, FWD could be switched in as well when needed.
There were also aftermarket freewheeling hubs to relieve the drag of of the unused front axle when in normal RWD on the road.
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In most old school 4x4s RWD is the norm, with a manual switch to 4WD, and usually low/high ratio selection too. In these systems you are either in full RWD or full 4WD, with or without central and rear diff locks.
Modern 4x4s and "soft-roaders" use variations of systems that can intelligently (or otherwise!) send traction where it's needed. Sports cars (e.g. Audi quattro applications) may be rear biased, others (your typical small 4x4) will be FWD and only allow the back wheels to kick in if traction is lost at the front. You might also have diff locks on these systems too, but it is less common.
These systems often use torque sensing clutches to control the amount of power sent between the two axles.
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I suspect part of the reason is that many modern 4wd cars, take my 4x4 Panda as an example, are adaptations or use drive trains that are adaptations of front wheel drive vehicles. Hence development costs are lower to add on rear wheel drive.
Older 4wd vehicles, such as the Nissan Terrano 2 that I used to drive, were designed as 4wd from the start with longitudinal engines, gearboxes and transfer boxes. In addition, ladder chassis put design constraints onto the vehicle favouring the main drive being rear wheel drive.
Would not swap my Panda with mainly front wheel drive for any of the older designs, much safer and predictable handling.
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