The post below is also cross-posted at Indian Autos Blog.
Early Jan this year, GM’s product “Czar” and vice-chairman of global product development Bob Lutz announced that GM is cancelling development of the next generation Zeta large RWD car platform, citing difficult economic and environmental concerns as the reasons. The most popular models spawned from the current GM Zeta platform (also referred to as GM’s Global RWD platform) are Chevy Camaro and Holden VE Commodore.
“This is because, whether you are in the United States or in China, fuel economy mandates are getting more and more severe, and we just could not base our strategy on doing relatively large and relatively heavy rear-wheel-drive cars,” Bob Lutz, Vice-Chairman, GM Global Product Development.GM is not alone, Ford Australia too has mulled over possibility that its hugely popular Aussie Ford Falcon will eventually be a FWD model by the next model change. While one cannot imagine a FWD BMW, putting the Mini aside, the Bavarian manufacturer would need to look into FWD soon as the market shifts away from large RWD sedans in favour of smaller FWD premium cars. Mercedes currently has the FWD A-class but is hardly making money out of it due to its very costly “sandwich construction.” This will be dropped in a favour a more traditional design in the next model change, and Mercedes will be expanding its FWD models line-up from the current A-class and B-class to 4 models, including a CLS inspired A-class and a compact SUV derivative of the B-class.

Most car enthusiasts often expound the view that to attain driving pleasure, you have to go rear wheel drive. The excuse often given is that the set of wheels doing the steering should not be burdened to do the driving as well; the front wheels should just do the steering while the rear wheels do the driving. But is it all that straight forward?
With increasingly tough environmental and fuel economy legislation being drawn up not only by governments of Europe and USA but also developing markets like China, the future of mass market RWD cars seem bleak. UK will be slapping punishing taxes on high CO2 emitting cars, and many of these will be large RWD saloons while cars that emit below 99g of CO2 per km will be exempted from paying road tax, which increases rapidly as a vehicle’s CO2 emission increases. USA is implementing fleet wide mandatory minimum fuel economy standards via its CAFE regulation. China has been mulling imposing a combination of fuel tax and car taxes to encourage use of fuel efficient / zero emission vehicles. The regulatory trend for all the major car markets is clear. And car manufacturers don’t design an engine or transmission to only last a few years in the market. They need to ensure that their designs continue to remain legal all the major car markets around the world. In the light of all these, FWD suddenly becomes a more attractive option than RWD. Expect to see a surge in interest for compact FWD cars – which is good news if you are one of those who appreciate nippy handling small cars. Not so good if you are horsepower junkie.
But is FWD that bad? RWD powertrains might offer superior weight balance and the widely touted “driving pleasure,” but distance power must be transferred between the engine and the driving wheels meant that mechanical losses due to increased friction and added weight penalty from having more components meant that compromises in fuel economy and exhaust emission are inevitable. Of course, there will always be Ferraris and Porsches well into the foreseeable future, though they may appear in vastly different forms (read : diesel and hybrid). I am talking of RWD saloons, specifically BMW models – a brand who has made RWD as a core part of its identity.
I suspect a large portion of the car enthusiast market’s preference towards RWD is largely due to motor journalists’ constant harping on the superiority of RWD setup, not to mention BMW’s highly effective marketing. But if you would pause for a moment and think objectively, does RWD really matter in 90% of the time a car spends on the road? Can an average driver really appreciate the differences between FWD and RWD in 90% of the time when the car is pottering around city traffic or cruising along trendy boulevards?

Take for example the BMW 1-series – it is RWD and as such interior space is seriously compromised. But drive it back to back against a FWD Volkswagen Golf, or even a humble Ford Fiesta and you’ll be surprised how close these cars match the dynamics of the 1-series, not to mention their far more resolved ride quality compared to the BMW’s jarring stiff ride. Even BMW’s own Mini drives just as well, if not better than the 1-series, and it’s a FWD. Of course, BMW engineers knew it all along that objectively it made more sense to build a FWD hatchback. But pressure from the marketing guys meant that they had to stay true to their RWD only philosophy. For so many years, BMW have been preaching about the superiority of RWD and the 50/50 weight distribution of their cars. It is not easy for them abandon the corporate philosophy and PR mantra. This is the risk when one banks too much on one particular idea / technology.
RWD might work very well on cars such as Mazda Miata roadsters and Lotus Elise – these are cars developed for a very specific application and for a very specific group of drivers. They work very well in places like the Nurburgring. But in reality, a properly sorted FWD chassis provides a far more exploitable package to the average driver on most road conditions, without all the necessary compromises in interior space as in a RWD car.

Ford Europe’s chassis guru Richard Parry Jones (often referred to as RPJ) have produced some of the finest FWD cars in recent time – the Fiesta, Focus and Mondeo. As has Volkswagen, and to a certain extent even Honda and Suzuki.

A former Lotus chassis guru once said that during the development of the FWD M100 Lotus Elan in the late 80s, they tested a FWD and RWD European Corolla. Both Corollas had almost the same weight, same power, same tires and wheelbase. But it was the FWD car that posted faster lap times in both wet and dry conditions. Not to mention how much more spacious inside the FWD car was. Autocar UK was quoted calling the Lotus Elan "the quickest point to point car available." Lotus sales manual also mentioned
“The ride and handling engineers found that for a given vehicle weight, power and tire size, a front wheel drive car was always faster over a given section of road. There were definite advantages in traction and controllability, and the negatives such as torque steer, bump steer, and steering kickback were not insurmountable.”Think about it. Lotus guys are really horrible marketers. But they have some of the best chassis engineers in the world, making chassis tuning into some form of an automotive black art that only the guys at Hethel have mastered. So when they say FWD is good enough, I am quite sure they have a strong reason behind it.
Of course the next Elise returned to RWD because the advantages of FWD did not appeal to Lotus buyers, who loved subjective appeal of an over-steering car. But those in the know knew very well what the FWD Elan was capable of and what it stood for.
Audi’s Jorg Bensinger, the father of Audi’s legendary Quattro system once said all cars should either be FWD or 4WD. Image from Audiworld.

The main advantage of RWD setup is its balanced weight distribution and the ability to provide a progressive over-steering characteristic enjoyed by enthusiast drivers. But when car companies start ramping up the power output to a point that the car is undriveable without any electronic driving aids, then the choice of RWD becomes questionable as it goes against the whole “balanced” philosophy of RWD. Then RWD becomes nothing more than a marketing gimmick, along with those ridiculous horsepower outputs.

Many of the high powered uber-German sedans / estates are guilty of this. None of those German 500bhp-600bhp RWD German uber-saloons are driveable without electronic traction and stability control. Ego aside, a nimble small hatch / roadster provides a more fulfilling driving pleasure, uncorrupted by nannying electronics. Which why I am looking forward to a world of more better driving hot hatches and less 600bhp sedan / estate. Thus, I was pleased when the head of Mercedes-Benz’s tuning division, AMG’s Volker Mornhinweg announced that the horsepower war is over. It took a recession to bring these horsepower junkies down to reality. 600bhp cars don’t teach you to be a skilled driver. A small and agile car teaches you to be more sensitive to all your senses and promotes driving finesse. Plus their limits of handling are easily reached, thus they don’t lose traction and suddenly break away into a ball of burning flame at very high speeds.
In short, there are applications suited for RWD, FWD and AWD / 4WD. But it is not an infallible believe that one powertrain is superior in all types of cars on all sort of driving conditions, or that only RWD cars can deliver driving pleasure. As Ford Europe’s RPJ have shown, it’s all in the setup. The days of “King of Torque Steer” Saab 900 Turbo are long gone. Advancement in suspension and tire technology has removed many of those negatives associated to FWD. It is not perfect, but on the right sort of car, it sure is damn close to the best of RWDs. And as a bonus, you get a larger trunk and cabin space, better fuel economy and lower exhaust emissions which keep the anti-car lobby greenies and governments happy.




4 comments:
Questions:
1. What is the difference in absolute and percentage terms between 2 identical cars but with differing layouts of FF and FR?
- if the platform / chasis is identical or similar
- if the platform is built to the layout design
*Any example will do
2. The article points out that RWD is more a marketing job than an actual design advantage. "But is FWD that bad?"
- Is RWD that bad?
- Are there significantly more driver aids required for a RWD at 200+HP than a FWD at 200+HP? At 400+HP? any car at 400-600BHP is ridiculous irregardless the drivetrain.
*Seems to me that the preference for FWD in regards to driving conditions has been a preference to lose control in under-steer conditions than in over-steer conditions. Driver aids are available across the board.
3. What is the ratio total of RWD against FWD built-sold in 2007? Run a cross comparison against the buyers. I think you will find that RWD designs are aimed at a higher market segment or what marketers refer to as a more discerning client. So your "average driver" may need a little more definition - irregardless whether that clientele can appreciate the difference between FF and FR.
- BMW built a design philosophy around RWD but this is their identity. Sometimes, who you are does not make sense to other people. You could say that this is now a time for change given harsh socio-economic and environmental conditions. But I would much prefer to see BMW innovate their way out of the limitations.
4. Jon Bensinger wasnt too specific. An RF layout would not be acceptable as well despite being FWD.
Wow a long list.
But you did made some interesting points.
Q1. I doubt there is an "universally agreed" way to quantify in absolute terms, on the differences between a FF and FR vehicle. Even if you were to do it theoratically, how do you assign the individual weightage each of the criterias compared?
The decision to adopt FR / FF drivetrain is usually motivated by cost and the vehicle usage type. I don't think any manufacturer uses any absolute quantitative comparison in arriving at their decision.
Q2. Of course RWD isn't all that bad. Ok to make it clearer - a RWD on a BMW 1-series is clearly a marketing job as it did not yeild any significant dynamic advantage over its FF competitors. On a M3 however, or maybe even a 5-series, there is a clear advantage.
I think a high powered short wheelbase cars, with a lower moment of interia are able to change direction very quickly, but that also means they are inherently less stable. Couple that with the more lairy oversteery behaviour of RWD cars, I am more keen to believe that RWD small cars (200bhp hot hatches) require more driver aids. But I could be more though, Lotus chassis engineers might disagree...just my thought.
Q3. RWD are popular in the higher price segment as these cars tend to be larger, so space (and cost) isn't that much of an issue. But to put a large engine and all the accompanying FWD mechanicals for a large car would result a very nose heavy car. Case in point FWD large Audis.
I am quite sure the whole RWD only philosophy is causing a lot of headaches to guys at BMW Group HQ. You mentioned that you prefer to see them innovate their way around a problem - sounds very similar to Jeremy Clarkson poking fun at Porsche for stubbornly sticking on their RR layout for the 911, despite a very clear solution available. I doubt such "bulldozing" approach is still applicable in today's environment.
But I believe BMW engineers and product planners have already decided on FWD for the highly secret Project i, due its clear advantage in packaging, cost and urban use. The problem now is for the marketing and PR guys.
Q4. Was there ever a RF layout vehicle? Rear engine, front wheel drive Sounds pretty absurb. Jon mentioned that all cars should be either FWD or 4WD
Q4: Yeah, I cant find any examples of RF either. I remember reading about it, something about Nissan's Micra platform.
Q5: So we are looking at the optimising of car sizes/space due to mileage and cost considerations as the underlying assumption for FF?
Do you think this is more a knee-jerk reaction to the factors of high oil prices and a global recession?
Q6: What is the impact of fuel cell and hybrid systems on cars? Does FF have a distinct advantage?
Q7: Could you do an article regarding engine development sometime in the future? We have lots of interesting engine options but there seems scant comparisons between inline, boxes, Vs.
Q5: Yes. FWD layout is cheap and provides better fuel economy, two very critical criterias for city cars. In a way, you may see it as a knee jerk reaction, similar to engine downsizing in the US after the first oil crisis in the 70s. The global market shifted to being dominated by Japanese makes and never looked back since (though fuel prices is not the only factor, there were others like rising Japanese quality and reliability).
This does not mean the death of RWD. We will just see more focused application of RWD. Meaning no mainstream Chevy / Ford RWD sedan.
Q6. The beauty of hybrid and fuel cells is that the electric motors are driven by electricity. It is far easier to transmit electrical energy than mechanical energy. Gasoline-electric hybrids might still adopt FF, for the same packaging simplicity. But you can modify a HV's FWD platform to provide 4WD by placing the motors at the rear. I believe the Lexus RX450h uses this configuration. The tricky part is in the control systems to manage the power delivery between the gasoline engine and electric motor.
On a full EV or fuel cell electric vehicle - you can provide 4WD with very little weight or packaging penalty. Mitsubishi have pioneered their "in wheel motor," essentially integrated electric motors on each wheel hub. The problem, like all things without economics of scale, is cost. The MiEV didn't adopt this because it shares many parts with the gasoline powered equivalent i-car.
Q7. Not an engine expert. Doubt can contribute much.
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