TDI Transmission comparison
 

ok, so...my 2001 new beetle tdi is an automatic 4 speed. of course, i already understand that a manual is capable of getting better mpgs.

I've heard that having more gears such as a 5 speed or 6 speed can improve gas mileage immensely. Which, leads me to believe that the newer 2006 new beetle tdi automatic 6 speed would get better mileage.

However, I've chatted with a lady online who says it's just the opposite.

Also, according to the EPA's website, the 4 speed does better as well.

Can anyone help to explain this?

Being that we're all "BETTER" drivers, what could someone like me expect out of a 6 speed as described above?

Sincerely,
me

There are a few things that could be going on here. How does the lady you chatted with drive? And the next question would be, between the 4 speed auto and the 6 speed auto, aside of the extra 2 gears, was the final drive ratio affected? Where does she live ( terrain and temperature )? Fuel quality? Was there an engine / drivetrain calibration difference between your vehicle and hers? ( No doubt there was )

The driving style, you know, has the greatest impact on mpg.

Also, all the extra hardware spinning inside the 6 speed auto might impose a slight penalty in losses; but unless both cars are tested back to back with the same driver, same driving style, it's pure speculation.

did the EPA calculation methods change between 2001 and 2006? definitely seems that a 6-speed should do better if its effective top gear ratio is taller.

Look at the overall gearing ratios.
The VW DSG auto trannies would have longer gearing.

The Passat on natural gas, does a lot better on the highway with the long geared DSG7 than the short geared manual box.

the 2011 golf with a 6 speed automatic (no beetle listed) is epa rated at 30/42mpg (same mpg as the 6 speed manual) the 2001 golf with the 4 speed automatic is epa rated at 29/40 (5 speed manual is rated at 35/44).
But it really comes down to gear ratios and engine tuning, lousy gear ratios give you lousy mileage! the big advantage of a 6 speed tho is you can also tune the engine to run more efficient because you are not trying to make it run over as wide of a range of speeds so you can either get more power out of it or greater mileage.
But to get back to the 4 speed over the 6 speed question, Honda for a while offered their base model civic with a 4 speed manual, 4th gear was a bit taller even then the 5th gear in most other civics of that year so the engine would be turning slower and the spread in gear ratios in the other gears was just larger to make up for it, so the engine would rev up a little higher before you would shift, but your highway gearing was still your top gear and 1st gear was still a nice low gear.

Also, here is a link to the Diesel EPA MPG figures if you want to compare models and years. http://www.fueleconomy.gov/feg/diesel.shtml

I don't know about the 6 speed, but the 5 speed manual TDIs of my vintage routinely returns 5 to 10 mpg better than my 4 speed auto, under similar (AFAICT) conditions.

Alot of the newer manual transmissions tend to be geared for performance driving, instead of better gas mileage now, so the mpg gap is closing with newer and newer cars.

I can definitely see that as being a possibility, too. what kind of success could I expect by swapping for a 6 speed dsg?

that probably wouldn't even work.

the guys at my vw shop tell me that dsgs have a lot of problems. then again, they more than likely drive quickly everywhere they go.

Too dang $$$$$$$$.

Have you done any software upgrades yet or are you running stock programming?

stock

p.s. thanks for your posts!