Newbie question. Why is single motor configuration RWD? Hardware obviously all there to put a motor in front. Is it all about 0-60 and reducing wheel spin? Industry practice settled on FWD for some reason. Except supercars?
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RWD vs FWD
- Thread starter kbellairs
- Start date
RWD is superior for driving dynamics as well as acceleration. The ICE industry settled on FWD for weight, packaging and cost savings by having the driven wheels near the engine. An EV doesn't have the same constraints. Many lower cost BEVs are still FWD because their configurations are derived from ICE chassis and/or they needed to be built alongside ICE cars on the production line.
A great example is the Golf...e-Golf...ID.3 evolution. Golf and e-Golf are FWD. The ID.3 is RWD.
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Daniel in SD
(supervised)
Only advantage of FWD I can think of is stronger regenerative braking. Braking hard with only the rear wheels is a bad idea especially in slippery conditions.
One advantage of FWD is that is easier to design in understeer. In passenger cars I think that’s considered safer than oversteer as a failure mode when cornering too fast. Swapping ends while panic braking is not pretty. 911s were considered killers. Computerized traction control on RWD may have solved the problem. Can anyone spin a M3 RWD?
MrYenko
Member
I’ve tried intentionally kicking the tail out on mine, and no dice. The computer shuts your fun down immediately on sensing pretty much any yaw angle at all. The stability control is EXTREMELY conservative.
The P3D cars will get a bit sideways, but even then the computer is babysitting you. That said, the P3D I drove was one of the most fun cars I’ve ever gotten wheel time in. Not the fastest, quickest, or best handling, but holy *sugar* you couldn’t wipe the grin off my face with a hammer. The software torque-vectoring makes you look like a hero at all times. It’s amazing.
The P3D cars will get a bit sideways, but even then the computer is babysitting you. That said, the P3D I drove was one of the most fun cars I’ve ever gotten wheel time in. Not the fastest, quickest, or best handling, but holy *sugar* you couldn’t wipe the grin off my face with a hammer. The software torque-vectoring makes you look like a hero at all times. It’s amazing.
BMW 320s are supercars? Maybe you ment to say "except performance cars?" and the answer would be (my opinion) "tesla considers their cars to be performance cars"
You mean the industry settled on FWD for economy cars. The overwhelming majority of premium cars or anything that could be considered sports cars are RWD or AWD. FWD is less expensive, and easier for manufacturing. RWD is better for about everything else.
I had a somewhat-related question that came to me today. I remembered one of my favourite daily-drivers from the last few years - a 2014 VW Golf TSi. It seemed so well-mannered in all it did, with smooth and light steering (electric rack and pinion) and a pleasant ride, but a good solid feeling without shakes or wobbles. And the stability of FWD. This was the version with the multi-link rear end, which always helps a FWD car.
I wondered if any Model 3 drivers have come from the Golf 7 and can comment on whether the Model 3 provides similar fuss-free driving dynamics.
There have been some great FWD non-economy cars over the years - 1991-95 Alfa Romeo 164 V6 comes to mind (popular in the USA) which was the basis for sports car derivatives 1998-2005 Alfa Romeo Spider and Gtv V6 (not sold in the USA) - Alfa Romeo GTV and Spider - Wikipedia - the handling of either was a lot more secure than my 2007 Mercedes CLS (RWD). The Mercedes always had a few wobbles, particularly when striking bumps while powering out of a corner.
-Alex
I wondered if any Model 3 drivers have come from the Golf 7 and can comment on whether the Model 3 provides similar fuss-free driving dynamics.
There have been some great FWD non-economy cars over the years - 1991-95 Alfa Romeo 164 V6 comes to mind (popular in the USA) which was the basis for sports car derivatives 1998-2005 Alfa Romeo Spider and Gtv V6 (not sold in the USA) - Alfa Romeo GTV and Spider - Wikipedia - the handling of either was a lot more secure than my 2007 Mercedes CLS (RWD). The Mercedes always had a few wobbles, particularly when striking bumps while powering out of a corner.
-Alex
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Did not mean to imply it is all black and white. And when I say "economy," I don't mean stripper, I mean the mindset of the OEM (I used to be an engineer for one). FWD makes the cars less expensive to produce. VW GTI's are my favorite FWD cars, by a very wide margin. That said, not all RWD cars are meant to be sports cars. Mercedes hasn't built a proper sports car, outside of the McLaren SLR, in decades. I'd say since the '64 SL's. Certainly the large luxury cars are not sports cars, but they are RWD. The Ford Crown Victoria was one of the most ill mannered cars produced in teh 2000's......RWD. Sure, there are sportY cars that are FWD. Example, the Mercury Capri XR2. Or even the late 90's/early 2000's Cougar. Most of these are intended to appeal to the aesthetics of things. I'll take Honda as an example. Their Type-R's are some seriously cool cars. Civic, Integra, etc. But when they wanted a true sports car, they went RWD (S2000). I don't know too much about the Alfa, but just about every FWD "sports" car out there is a version of a more economy minded car.
But if slick and you brake hard with just the front the rear is more liable to swing around on you, so even then RWD is better.
FWD is more forgiving to poor driver's which is then thought of as better, but it isn't.
The RWD Tesla's need frequent tire rotation because the rear does all the drive and most braking, move that to the front and have the front tires do all the steering, all the drive, and an overwhelming majority of braking and you would really have to keep up on tire rotation.
Daniel in SD
(supervised)
That is completely incorrect. Brake systems are heavily front biased so that they lock up the front wheels first. Ever heard of a parking brake turn?
I prefer RWD. I don’t know which is statistically “safer” but I bet with modern stability control it doesn’t make much difference.
FWD is way worse. High performance FWD cars eat through front tires faster than RWD wear rear tires because you’ve got one set of wheels driving, steering, and holding 60% of the weight of the car.
I was referring to Regen specifically as it is tied to the drive wheels. Yes hydraulic brakes are usually something like 70/30 front bias.
Imagine heavy Regen kicking in front tires only on a slick surface.
Right, yes, I understand now and I agree
Great example there of the Ford Crown Victoria - not sold in Europe or Australasia but we know it as “that police car you see in movies and music vids such as ‘Sugar’”.
So - a RWD car that’s not sporty in any way and didn’t make it out of the USA/Canada and the FWD sports cars I mentioned which didn’t make it to the USA/Canada - it’s clear that there has been diversity out there.
I think the path Tesla treads with their chassis dynamics is probably more in line with BMW, which has been successful everywhere. Nice even weight distribution - helped by Tesla’s large battery in the floor - means that RWD, or rear-biased AWD, is the natural choice. Otherwise it would be like driving a heavily-loaded FWD van - such things do exist but are never the paragon of steering or traction; the front wheels just have too much to do.
-Alex
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I got to put a lot of miles on a Falcon when I was at Ford. Had our 5.4L V8. Man that was a seriously fantastic car. So much better than our Crown Vic. Drove like a BMW, but priced like a Ford. RWD, of course.
The clown Vic(deliberate) had no competition so why do anything but build it cheap. In the 90s it and the Caprice were the "cop cars" but we're 70s chassis. Not enough cash in the market for both to be redesigned Chevy blocked first and Ford did a minimum and kept the model around a lot longer. No competition till the charger built on an outdated Benz platform meant no reason to put cash into making it good.
Daniel in SD
(supervised)
Yes that would be better. No difference between regen and friction braking. There's a reason FWD EVs have stronger regen than RWD Teslas.
Sport bike riders have dual disks in front and a tiny disk in back. Mostly trained not to use back brake. Rear is loose and along for the ride.
Leafdriver333
Somewhat Active Member
I'm surprised that no one yet has mentioned snow and ice.
Because we live where the roads are sometimes slick in the winter, we coughed up the extra money and waited a whole extra year for the dual motor M3.
I have never driven the single motor M3 on ice so I can't speak to that. But I can say that almost everybody who lives in snow country understands that front wheel drive is much better than rear wheel drive, at least in ICE cars. ...We're not talking about stopping, as that can be applied evenly with brakes, we're talking about accelerating where when the car is pulled with the front wheels it tends to squirrel around less on ice. If only pushed by the rear wheels it can spin around. (Not sure if the M3 does this or not).
But I have an open mind. At the time we had to make our decision, I could find no good source of info for how the M3 rear wheel drive does on ice, and we weren't willing to risk getting the wrong model. I suspect this is the reason that I heard that dual motors are outselling single motors.
Still, I someday hope to drive a rear only M3 on ice on a safe open parking lot just to see how it does.
Because we live where the roads are sometimes slick in the winter, we coughed up the extra money and waited a whole extra year for the dual motor M3.
I have never driven the single motor M3 on ice so I can't speak to that. But I can say that almost everybody who lives in snow country understands that front wheel drive is much better than rear wheel drive, at least in ICE cars. ...We're not talking about stopping, as that can be applied evenly with brakes, we're talking about accelerating where when the car is pulled with the front wheels it tends to squirrel around less on ice. If only pushed by the rear wheels it can spin around. (Not sure if the M3 does this or not).
But I have an open mind. At the time we had to make our decision, I could find no good source of info for how the M3 rear wheel drive does on ice, and we weren't willing to risk getting the wrong model. I suspect this is the reason that I heard that dual motors are outselling single motors.
Still, I someday hope to drive a rear only M3 on ice on a safe open parking lot just to see how it does.
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