The emission controls that medium to large diesels need are very expensive (smaller diesels are merely expensive). That, combined with a high cost of diesel, makes them a money losing proposition in most scenarios. Plus turbo DI gasoline will bring gasoline cars closer to diesel for mileage -- at least that's what Ford and GM are saying.

In any case, the U.S. probably does not have the extra refining capacity to add a bunch of diesel cars to the fleet, so it's just as well not to go adding a bunch of diesel demand to spike the price even higher.

 

I disagree. A rear axle loses in the range of 7-12% of the energy that is tranferred though it. Any energy lost through the drivetrain means more energy must be generated at the engine to propel the vehicle, meaning more fuel will be consumed. BTW, any reputable powertrain company has numbers published internally that could easily compare powertrain losses between FWD cars and RWD cars. They just choose not to share the data publicly.

 

Sure looks like theres some sort of change in angle in there...

 

You are correct that there are changes in angle, but the energy transferred through the transmission is never diverted 90*. When you transfer energy 90* (like is done in a rear axle) it is much less efficient than maintaining the engine parallel to the drive wheels, like this transmission is. By looking at this transmission, you can see that the torque converter is still parallel to the axis that the half-shafts will slide into. If you were to place an engine in the rear of a car, similar to what some sports car companies do, and place the engine parallel to the drive wheels you would have less power loss like FWD cars.

 

I just don't think it's significant, because mileage variation between FWD and RWD cars with the same power train is not significant. There's more variation due to engine, transmission, or gearing.

 

The flaw with Ford basing a crown vic replacement on the Taurus platform would be...the whole point of the car. What is the point of another car roughly the same size as a Taurus, with the same platform and drivetrain? Might as well just cancel it and make a cheaper Taurus and hope it sells to cops/taxi drivers.

I just hope some companies fill the void for RWD cars that don't cost a fortune.

 

Might as well just make a 4" stretched version of the Taurus for those markets like they do with the current Crown Vic.

 

Overall, a VERY GOOD ARTICLE, Guy, on CAFE thoughts!!

Two points of clarification:

(and I'll do this in two posts...)

First point-- you wrote:

".........A car like the Ford Shelby GT500 and Chevrolet's ZR1 Corvette do not affect each company's CAFE rating because both are sold in such small quanities versus the sales of the entire company. Meanwhile, the sales of family sedans have a dramatic impact on CAFE......."

.......is not an entirely true statement. No question that a car like the Impala or Camry DOES have a very dramatic impact on CAFE.....(and this has a lot to do with the post that will follow this one...) The numbers alone (300,000 Impalas a year versus 34,000 Corvettes a year) will illustrate that.

However -- the Corvette and Mustang -- (and GT500 and ZR1) DO affect CAFE -- their numbers are also included in the calculation.

That said -- each 'car line' is given a 'target' that must be hit.

You are correct in that we STILL don't know EXACTLY where the CAFE standards will be by 2020 -- and that's because laws have been drafted......

.........and passed......

.........and repealed.............

.............. and sent to the dry cleaners..............

................. and given a time-out.................................


(sorry - couldn't resist the last several words......)

.........but the CAFE laws are STILL very much in flux!..........

What we DO know is that your very own Henry Waxman....

(.....unless suddenly hit over the head or suddenly does a 180 degree turn from where he's been the past 'forever' years)

-- will -- at minimum insist on 35mpg by 2020; but a lot of people think he and the new administration will insist that it be raised even more.......

That will impact cars like the Corvette and the Camaro and the Mustang.......

......what we DON'T quite know is by just how much.

I have the advantage of seeing where we must go in the next couple of years -- based on some conservative assumptions......

........if gas goes back up again, Americans will buy more fuel efficient cars --and that drives the CAFE average attainment UP -- and that may very well allow us to build performance cars.

BUT - (and keep in mind that I'm speaking for ME - not the company I work for.......) if gas moderates, I suspect many Americans will go for size and comfort and performance........and that would draw the average down -- and as a result, it would impact how many performance cars we could build -- and/or it could affect driveline performance.

The wildcard: Technology..........which is developing at a very fast pace. If gas is high and we sell lots of cars and trucks with Volt and Hybrid Technology -- we may all be surprised at CAFE attainment!.........

 

................second point:

You wrote:

"........Bob Lutz claim that the RWD Impala was killed over a 1 mpg difference was either false or shows that GM's decision making process is still extremely disfunctional.

..... or perhaps GM should hand over the helm to their Australian Holden division, since they seem to know how to do things GM's North American division find impossible........."


Two issues:

1. One must take into context WHEN Mr. Lutz made that statement. The statement was made right after laws were passed .....BUT ....and this is important..........the RULES on how to meet the standard set forth by the laws had not been written - and, in fact, I don't believe they've YET been finalized as I type this. (that said -- I'm not privy to CAFE in day-to-day responsibilities -- it's not something that's sent to every man/woman/child at GM!)........


2.....RWD HAS been, for the most part, handed over to Holden.......and I don't know that I can agree that the decision making process is still dysfunctional. (note I said 'still'....) Decisions are now made on a Global basis -- and have been for some time!


......and -- linking back to my previous post -- IF one were to build 300,000 RWD Impalas, there is evidence that this would have negative impact.

(I should also point out that there are those that claim that IF we were to make the Impala RWD, the volume would drop significantly - and consumer feedback tends to agree.....)





Now.......(and again, Gentle Readers.......I must say, once again, this is MY outlook and my opinions and not necessarily those of the company for which I work.......)

I thought the RWD Impala proposal was just KILLER.........


(.....it took three weeks to get the silly grin off my face after seeing two proposals......)



In closing - -good insights, Guy!


(one last thought: I've had about 8 hours of sleep in the past week.......so my mind is even more fuzzy than usual.....so I hope all of this made sense....)

 

So, what are the chances that the public will ever get to see what we've been hearing about for months? Everybody who has seen the RWD Impala designs that has been allowed to say anything about it in public has raved about how nice they look.

 

I suspect some elements of the design will end up on the "Espilon" Impala, due out in a couple of years. There are a different set of hardpoints & the proportions a slightly different (mainly FWD has far more overhang up front), but the Espilon 2 of the Impala and the Zeta it was initially to be based on are very close if not near identical in size. No automaker simply throws out a good design if they can use it on something.

But.... If a drawing or two of the Impala are on the wall in the background in pictures from GM's design studios in the upcoming book on Camaro's development... that might give a clear glimpse a bit early, or at least what the design looked like before it was modified. That would be a nice treat.

 

 

Can you elaborate on the differences or provide a link to more info?

No, there isn't. Gears are one of the most efficient ways to transfer energy; the incident angle is irrelevant as long as the teeth mesh.

 

I posted previously in other threads. In brief, the CAFE number is based on the raw EPA data, whereas the numbers on the window sticker and EPA website have been adjusted downward to be more realistic. It used to be that city was decremented 10% and highway 22%. I don't think they use a fixed number any more, but it's more than the above, since everyone's numbers went down in 2008.

If you go to epa.gov and look around you can find the raw data in .csv form. Let me know if you can't find it, and I'll look it up later when I have time.

 

My 96 impala has a LOT more front and rear overhang than my wife's 04 impala...

I have noticed that FWD cars generally have the rear wheels further back in the chassis than RWD cars.