Poor MPG on a New Rabbit

[rjemery]

I recently purchased a 2008 Rabbit with Automatic Transmission. Government fuel economy figures for this vehicle are 21-29 mpg. In the first few hundred miles of driving, I find I am getting 22 mpg, much worse than I anticipated, and well off the 28-30 mpg I got from my previous Golf 5-speed manual for the same mix of driving.

When I complained to the salesperson about the low mpg, he explained that I am still in the break-in phase, and it won't be until about 10,000 miles are on the car before I will see peak efficiency.

I am suspicious of that comment. In my experience, the best mpg comes when the car is new, but I don't have much experience with late model cars. By way of example, it was a surprise to learn that manual transmissions no longer offer much of an advantage over automatic transmissions.

Is there any truth to the salesperson's claim?

[HeavyJ]

Three things: Its new, it will take some time before you see the best mileage, Its winter, fuel mixtures play a part in lowering mileage, and don't ever believe those EPA figures on the window sticker, a bunch of baloney.

[UncleBob]

the "break in" is a bit of an old myth. There is no real break in anymore. The car won't be much different from mile 1, mile 1000 and mile 10,000


That being said, two different cars. I wouldn't assume just cause they were both VW that they should be identical mpg for the same driving habits.

[slideways...]

yeah the rabbit is heavy and should get mid 20s for mostly city driving. and it should not be compared to a golf. but its driving style also. i usually get around what the average mpg rating is, but my parents have gotten 5-15 mpg higher than the sticker rating in every car they have owned. their 03 civic EX 4 door gets 50mpg highway and low 40s city.

[KiwiBacon]

I'm finding modern cars take 200-300,000km before the engine starts to loosen up and improve fuel economy.
One example in particular is a 95 (96 model year) honda accord which is now getting 3km/l more on the open road than it did when it was new.

[slideways...]

slap on a better flowing air filter and muffler. you should notice a couple mpg better on average.

[rjemery]

Originally Posted by slideways...

slap on a better flowing air filter and muffler. you should notice a couple mpg better on average.

What is a "flowing air filter," and how does it differ from a standard air filter?

Can one of these be installed on a 2008 Rabbit without modifying the housing?

[GreyGoose006]

no no no... better-flowing air filter.
as in an air filter that flows more easily.
k&n is a popular brand, but honestly, i wouldnt hold out much hope...
you will see maybe 2% difference, which means that if you had 20mpg before, you have 20.4 now.

yes, they can be installed without modifications.

[rjemery]

Originally Posted by GreyGoose006

you will see maybe 2% difference, which means that if you had 20mpg before, you have 20.4 now.

OK, thanks. A 2% increase is trivial. I wouldn't want to risk warranty issues over that. VW goes bananas when they see non-Bosch replacement filters and will claim the use of such parts voids the warranty if anything untoward should happen.

[GreyGoose006]

well it wont void any warranty.
K&N should have a guarantee or something.
but i do agree that the difference is trivial unless you go and do a fully custom cold air intake and exhaust...

[KiwiBacon]

Free flowing air filters do not aid economy on a petrol engine. Neither do cold air intakes.
Both are power mods only.

IMO K&N filters should only be run in environments so clean you don't need an airfilter (i.e never).

[drunken monkey]

something not mentioned:

mpg figured are calculated using a start-stop process to "simulate" driving.
how you drive and the journies you do may not match the (inaccurate by nature) mpg figures.

typically, the mpg figures in the US are higher than real figures which is why they are implementing a new testing system.

[UncleBob]

Originally Posted by rjemery

OK, thanks. A 2% increase is trivial. I wouldn't want to risk warranty issues over that. VW goes bananas when they see non-Bosch replacement filters and will claim the use of such parts voids the warranty if anything untoward should happen.

you are correct, it will void the warranty on any future MAF replacements (something that fails often anyway)

Any time I get a car with a P0721 code, first thing I check for is a K&N filter

I personally don't recommend it, thats for sure. (not on a vehicle with a MAF sensor)