> not doing anything dumb like accelerating through the curve
Is this dumb in winter, or dumb generally? I was taught to do this.
Is this dumb in winter, or dumb generally? I was taught to do this.
If you want to maximize speed through a curve plus straightaway, you should pick a path through that curve minimizing curvature at the end so that you are able to accelerate out the end of the curve. As a reasonably good approximation for normal driving, your tires have the same traction regardless of the direction of the load being placed on them. That gives you a budget of net force you're able to apply. If you're near the sideways force limit going around a curve and add acceleration (or braking -- always do your braking before you enter the turn, or gradually reduce it as the curvature increases), the wheels with those extra forces will break traction. The solution is to apply that acceleration at a point of milder curvature.
Taking that idea back down to safe driving speeds, the same idea exists when considering crossing a margin of error rather than the ultimate slip threshold. All else equal, accelerating as you come out of a curve, if you've chosen your path through the curve correctly (really important to get that right; there's a curve back near my hometown which has taken out half a dozen people over the years because its curvature increases at the end and they haven't planned for it), will minimize your time through the curve and the following straightaway at your chosen safety threshold.
However, all of that is predicated on minimizing time assuming perfect knowledge and perfect driving. The acceleration itself is actively harmful from a safety perspective. In FWD, the wheels losing traction are the ones connected to your steering wheel. That's not ideal. In RWD you're prone to oversteer and spinning out of control. In AWD you can get either or both of those failure modes. Moreover, navigating typical curves, you're so far from slippage that the technique of accelerating at the end just means you'll go from the speed limit to something greater. For winter curves, the margin of traction uncertainty is so great that you can't gain much from accelerating out the end anyway (and have a pretty bad risk profile -- accelerate on a straightaway and slip a bit and with a bit of training you're basically fine, slip off a curve and you have a really bad rest of your short life potentially).
Safely accelerating in a curve is a learned skill though, and most people don't care that much about driving. Unless it looks like they're interested in more depth, my advice is always to brake before the curve and accelerate afterward. It's safe, fast enough, and easy to remember.
- Smaller turning circle because the front wheels can turn further without complicated engineering.
- More traction when accelerating on a wet surface, due to weight transfer backwards. (1)
- Usually better weight distribution due to engine layout.
There are other downsides in addition to what you mentioned:
- Any scenario where you will definitely lose traction, then rear-wheel drive becomes harder to control. There was an old Top Gear episode with a steep grassy hill, and drivers of the RWD cars could not get up it. (2)
- The transmission tunnel required for RWD
- Reduced fuel economy due to having to turn the power 90 degrees (assuming the engine is mounted in the front). (3)
1) This one may sound like unnecessary acceleration, and it probably often is, but there are situations where it can arise, especially if you prefer older cars. There is one particular hill I used to encounter frequently, where you are trying to turn onto a main road, so you want to accelerate fairly briskly to avoid waiting for a huge gap in traffic. On economy tires, in the wet, you can easily reach the limits of FWD. I would see many cars time a gap, and then have to rapidly decide to give up on it when their acceleration was much slower than they expected due to wheel spin. I think there may have been bus lane paint on the road too, but I'm not certain. Obviously AWD is even better than RWD for traction, but at that point, that is usually only when requiring rapid acceleration.
2) I suppose with perfect/computer assisted driving, RWD would out-perform FWD.
3) I once searched, and had a very hard time quantifying this, but it is almost certainly a few percent, and perhaps more. There are also weight differences involved because of the long drive-shaft, but I think the effect is larger than that. It is very hard to find an apples-to-apples comparison.