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Rear wheel drive

You may want to rethink the rear wheel drive on the Model S. I guess performance on dry pavement is best with real wheel drive but that is not the case in difficult conditions. Front (and of course all wheel) drive vehicles are sooo much better in snow and ice. I would much rather be in my old Honda or even my old Plymouth van in snow than than in my current BMW. Please reconsider.

Timo, I am not disputing the icy-hill-scenario. Obviously, on a slippery slope, you'd need every bit of traction you can get, at the expense of most everything else. Also the author of the blog post I linked above does not deny this.

The point of the argument is: In all other situations, RWD is actually better (assuming short/light overhangs, low center of gravity and even distribution of weight between front and rear axles). Everybody has to judge for himself/herself: Which situation is more typical for my driving needs?

I guess, why I bring this up, is this: There is a tendency to see AWD as an option that improves handling in some situations and has no negative effects in others. But that's not true: If you optimize for 1% slippery slope driving, you still have to carry the burden of the AWD for the remaining 99% of your driving. Either way, it is a compromise. It is easy, but unfortunately wrong, to assume the AWD is "simply better".

I've had an AWD subaru, and have auto 4wd on my Explorer. Most of my other cars have been RWD. My wife's current car, a Volvo C70 is front wheel drive though.

I HATE fwd. I can't stand the feel of it constantly fighting me for control of the stearing wheel when I'm accelerating while cornering. And her front wheels break free easily on wet pavement, especialy when starting from a stop on an uphill slope. We used to have a steep uphill gravel drive, and it was constantly being ripped up by FWD cars.

So FWD is not allways a better option. It's only effective when the car is front heavy, eiether from the engine, or from not going up hill. But mostly, I hate the torque through the steering wheel.

AWD, when made properly, is "simply better" when you talk about handling. If you value everything else as high, then you can say that RWD might be better...when you are talking about ICE car. With BEV AWD with very precise traction/torque control between front and rear wheels is a lot easier to make.

AWD, when made properly, is "simply better" when you talk about handling. (Timo)

I know this is starting to become a religious discussion, not unlike Apple and Orange, eh, Microsoft. Yet, I stand by the obvious: Even in conditions where you do not need AWD at all (which once in a while, if not most of the time, will be the case even in Finland) you have to carry around the weight and complexity of front wheel propulsion. Even if the front motor is unused and front wheels are not propelled, handling will be negatively affected because steering is more complex and the front axle is heavier to support propulsion "just in case".

I'm not going to convince any die hard AWD enthusiasts, and I'm not even trying. I don't know where you live, but where I live and where I drive I'd like to have AWD for around 1% of my driven miles (winter holidays in Switzerland) and for the rest I'll not be just as happy, but in fact much happier with plain ol' standard RWD.

Think of it this way: Traditionally, AWD is a cure to problems the Model S does not have in the first place (long/heavy front overhang, uneven weight distribution, high center of gravity). Yes I know, the icy-hill-scenario. You are right. I said that.

Also, as I said before, I concede that many of the massive disadvantages of AWD in ICEs are mitigated in a BEV vehicle, but the gist of it remains true. There is no free lunch. It is a compromise either way, and it is up to each individual driver/owner to decide whether or not the pros outweigh the cons. I am curious to see data (weight, range, prices) revealed for the Model X RWD vs. AWD versions.

I forgot to explicitly mention larger turning radius as one of the obvious disadvantages of FWD and AWD. That's something most drivers will suffer every single day of their driving life. Does the very specific advantage of AWD outweigh this disadvantage? Definitely yes for some drivers, but not for me.

Question is not about needing most of the time, it is needing for that small amount of time. For most of the time you can do with single wheel drive without matter which wheel it is.

Timo, you should not settle for less than a chain-driven tank. Best traction, and best passenger protection. Just in case...! ;-)

You are exaggerating to illustrate your point, and so am I. There is no denying that we must make compromises. Single-wheel drive may have some advantages, but with my requirements in mind, I prefer both rear wheels driven and I accept the disadvantages that come with it. I do not want chains on my vehicle although there is a chance that chains would save my life or that of my family in some situation in the future; the disadvantages are just too big and the odds too small. With regard to AWD, you have different requirements and priorities than I have, and therefore our assessment of the advantage (one single very specific advantage) and the disadvantages (many in theory, the importance of which in daily driving is debatable) leads us to different results.

My wife bought a 2012 Acura TL Advance some months ago. It's got what they call "super handling all wheel drive" (SH-AWD).

She got it because we have hills and snow, and, as you say, about 3 times per year it makes her feel more comfortable about going to and from work.

I must say, though, powering around clover leaf entries to highways is really, really good with this car. It's programmed for different power to different wheels depending on the situation. Then again, it's been a long time since I've driven a RWD car with any power and no one else in the car. I'm looking forward to seeing how a powerful RWD car compares.

I was thinking a lot about this lately as I had to drive in snow and ice for a week in my FWD car, and I was thinking how great it was to have the drive wheels also be the steering wheels.

I know that RWD is sportier or whatever, but I'm kind of worried about it.

I think I would not absolutely need AWD but it would be very useful to me. I live in a place where it is hill in every direction. Just to get out of garage is a quite steep slope. Just few days ago I watched in delighted horror how one of those crossover things with all-season tires slide sideways down (literally down) the street (got out of parking space next to my apartment and immediately started to slide). It somehow managed to not hit anything.

Having driven AWD:s, RWD:s and FWD:s in winter and actually having trained for slippery condition driving I really appreciate the extra grip AWD gives in those conditions.

(I hate tanks, they are cramped smelly and loud things. I prefer light APC:s with capability of crossing rivers and swamps).

I asked about Tesla's performance in ice and snow at the Santana Row store today, and their answer is really clear -- the Roadster handles very well in ice and snow, and the Model S will beat or exceed that performance.

An interesting video here. I've seen others, similar, that show the Roadster coming to a full stop on a snowy hill and starting up again without even a hint of slipping.

IMO, driving on snow just requires having the right tires and the right driving technique. I think the only thing FWD gives you is a little additional traction from the weight of the ICE.

And the battle between various drive wheel configurations continues....

As Volker points out, they all have their advantages and disadvantages. FWD cars like Mini and Mazda dominate the SCCA racing series. Move up to the big powered cars and thay are all RWD. A couple teams have tried AWD in Formula 1 for instance, but that series is dominated by RWD. Rally cars and off road races are dominated by the AWD for obvious reasons.

So it all goes back to what's most important to you. Small FWD cars are a blast to race in corners. Big powered RWD cars can be a breathtaking accelerating experience. AWD can get you out of slippery situations the others would wreck in. (And will also get you into deep doo doo when you don't understand AWD has very little assistance to braking or cornering!)

My 2 cents.

FWD once saved my life. I was in mountain roads, in a FWD Honda, and a corner came up suddenly that had had a recent "gravel fall", just enough to sprinkle the road with ball bearings. As I slid towards the fall-off, I instinctively lifted my foot off the gas and then "blipped" it. The wheels spun the gravel out of the way, contacted pavement, and pulled me around the corner.

That was about 40 yrs ago, and is vivid in my mind to this day.

And will also get you into deep doo doo when you don't understand AWD has very little assistance to braking or cornering! (BruceR)

Just thought this is worth repeating... ;-) Audi Quattros seem to fly off the corners in winter more frequently than other cars, probably due to their great traction in forward motion -- the drivers lack the sense for the real slippery outside conditions. Of course that would not happen to any members of this forum, as we are all conscious, careful and trained drivers and won't be so easily betrayed.

Timo, wrt the SUV that you watched sliding down sideways... I wonder how AWD would have helped that situation? If it is not even possible to come to a standstill, i.e., if traction is similarly close to nothing in any direction and tires even slip sideways -- the situation would only become worse when you start spinning all wheels.

All-seasons in snow and ice suck. Save money by not buying winter tires, and cost yourself lotsa body work, maybe for both you and your car.

V.B, it wouldn't, but gives you (and others) a picture of what kind of place I live. I would obviously get for my Tesla car set of decent winter tires and not some slippery all season tires. I think whoever did own that car does so also in the future.

Happens here in Vancouver, too. Snow is rare enough that lots of the clueless have all manner of semi-comical trouble. The heavy-foot tire-spinning ices up the roads for the next guys, too.

OK, I'm now a believer in RWD for EVs...let me explain.

On my business trip to the Bay Area this week, I rented a Nissan Altima Hybrid. Very nice car in many ways, but severely marred by the steering/handling. I could tell, absolutely, that the front wheels were simply being asked to do too much: ICE power, EV power, EV regen, braking, and steering.

Shifting some of these responsibilities to the rear would have left the front with just steering and (half of) the braking, which would have been a much better driving experience.

For the fun of it and slightly off subject, I call your attention to this You Tube vid - not all AWDs are equal.

FWD, RWD, AWD … in all cases, when driving in adverse conditions you should engage your brain and common sense.

http://www.youtube.com/watch?v=ooQRxlChvMw

This is the aspect that I am most nervous about, even though it will only affect me a few days a year (though potentially a lot more if I need to worry about wet roads too). I ahve never driven a RWD car.

I live and work in the Pugent Sound area around Seattle. To leave and return to my home city, I have to go down and back up large hills which are also curved. Whenever it snows, the snow usually becomes ice within the next day or two because of the mild and wet weather we have. When this happens, I always see some RWD cars and trucks which cannot climb the hills.

Does anyone know, with the Model S, or the Roadster, for that matter, to the non-drive wheels freely turn? That is, if you put the car in Drive (D), and were to lift the car off the ground, would you be able to rotate the front wheels backwards using your hands? Or does something "lock" the wheels into only turning forward. I'm not even sure if that would make a performance difference, but I'm just trying to imagine what it would be like trying to go uphill and turn at the same time in a low-traction situation.

Th non-drive wheels usually turn freely as far as I understand it from my experience changing wheels and brakes on my cars.

Yes, the non-drive wheels definitely will turn freely. This is not just normal but universal on cars with drive at one end or the other.

olanmills, the Tesla Roadster has RWD, just as the Model S. Maybe you find some these videos interesting to watch:
http://www.youtube.com/results?search_query=tesla+roadster+winter
http://www.youtube.com/results?search_query=tesla+roadster+snow
http://www.youtube.com/results?search_query=tesla+roadster+ice

Turns out that with its even weight distribution, long wheelbase, low center of gravity and top notch traction control, the Tesla Roadster is an excellent winter car -- and IMO it's unlikely that the Model S will be any worse.

Cool, thanks.

Tires, tires, tires. Get some Nokian snow tires and you'll be just dandy!

One detail to keep in mind: On a steep incline, weight shifts to the rear axle. With weight shifting away from the front axle, driven front wheels will increasingly less likely be able to pull it off (intentional pun). Thus, maybe counter-intuitively, the Model S RWD with its low center of gravity may actually be better in some situations than an AWD Jeep. (No doubt there are more tough-terrain situations where the AWD Jeep will have advantage over the RWD Model S.)
http://www.youtube.com/watch?v=H6VLSFSMCsI

There are two forms of "Traction Control" that are used in many cars.

One method applies the brake to the wheel that is spinning or starting to spin. Because a differential is a constant torque device that allows the wheels to turn at different speeds, if one wheel has no friction, it will spin at nearly zero torque; this then puts nearly zero torque on the wheel that has friction. If the brake is applied to the spinning wheel, this puts torque on that axel and thus puts torque on the wheel with some traction, and the vehicle can start to move. I call this real traction control.

Another form that is used in the Prius and the Tesla Roadster 1.5 that I have senses a spinning tire and then reduces torque and power from the motor to the wheel. This helps reducing spinning by applying less force, but if there is nearly zero friction on one wheel, it can be very frustrating to have nearly zero power applied to the wheels and not move. I have experienced this many times in a Prius that I used to own and the Roadster 1.5 that I currently own. BTW, I call this anti traction control.

Here is a video of getting up the driveway at my other home in the Rockies, called Hole in the Wall. The last pitch before the house and after the last turn is a 15% grade. All I want is an electric vehicle that can make it up this most of the time in the winter. Even my jeep with air lockers and good snow tires can't make it up after a 2 foot, 60 cm snowfall until its plowed. The worst case conditions are when the winter packed powder is melting in the spring and the road is covered with slushy ice. Then the only thing that will make it up my drive is my ATV with 4 tracks in place of the 4 wheels. Most of the time, if I put chains on all 4 wheels of the jeep I can make it up, but that is a serious pain...

https://www.youtube.com/watch?v=0lKoHO3AEPk&list=UU0jDCIQFr4H_-Gybc-lbmFw This video was done in a 4WD Chevy pickup in low range with the transfer case locked.

As far as I can tell the Model S will have "Real Traction Control." The Model X has two motors, one for the front and one for the rear, somewhat like the Lexus Crossover hybrids (400h and 450h). I have driven the 400h and it is pretty good in low traction situations. If the Model X with its two motors has real traction control front and rear, it should be excellent in low traction situations.

BTW, my approach to my driveway in the jeep is to use my air lockers. They allow me to lock up or put all the differentials in solid mode, as if it had solid axels. On solid pavement, this mode is difficult to steer, and grinds up the tires, but if one wheel has traction, the jeep will move. On snow, grinding the tires is not an issue; the snow gives. The comment on tires is very true. In the winter, I only use good snow tires.

The Range Rover in the video from the last post ran out of torque, not traction. If she had put the Range Rover in low range and turned on its traction control (one of the best made), it would have gone all the way to the top, no problem. I have climbed such hills in my jeep and in Range Rover test drives. BTW, the Range Rover traction control, works on all four wheels, applying brakes to any wheel that starts to slip.

I have been assured that the Model S, competing with BMW 5 series, etc, has real traction control. I have to assume that the Model X will have real traction control front and rear. My question is do I wait 2 years for the Model X or take my Model S reservation this year...

The real question is this:

If tesla offered AWD as an option, would you consider it?

If it cost $500 and range loss was only 3%, I think we would ALL ADD THAT OPTION!!

In reality it is just a matter of how much $$ and possibly how much change in RANGE. I know I would be willing to pay a couple $k for this. Especially if the design is such that 99% of time it is RWD

Btw I drive GT-R. Great car, inspires incredible confidence with AWD and MANY MANY electronic systems for stability, grip. Including accelerometers. But during a recent FREAK snowstorm, I was able to get where I needed to go with the practically slick tires... If we had more than 3 days of snow here, I would have to buy different winter tires... I also feel much more confident in rainy conditions. But you must "drive for the conditions". I spun out my Subaru WRX pretty bad in icy conditions one day, four wheel spin BAD!! Not much traction control systems on the '03 WRX

The wife's FWD Volvo XC90 usually ends up powering ONE WHEEL when pulling out into traffic... Not at all confidence inspiring... When one wheel slips and it takes car 2-3 seconds to institute power transfer...

Subaru makes symmetrical AWD vehicles. Subaru demonstrates the superiority of their system on YOUTUBE.


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