How do I improve the poor fuel economy with my 2003 Jetta Wagon TDI

I purchased a used Jetta Wagon TDI 3 weeks ago. I purchased it from a dealer claiming it gets up to 50mpg highway. I've also read that these cars can get between 700-800 miles per tank of diesel. My last tank wasn't even 500 miles. The average miles per gallon was around 32, and at least half of the driving was highway mileage. Does anyone know why my fuel economy might be suffering, and what I can do to maximize its efficiency? And I drive conservatively, I don't have a lead foot. Thanks for any help or assistance .

Bet your intake is clogged.

Automatic transmission?

And did you believe a salesman?

First, you probably don't have accurate FE data unless you've filled the car several times. Second, automatics will get FE in the 30s when driven reasonably hard. Third, there are an array of things that you should check to make sure your car is running as well as it can, including timing, intake cleanliness (as posted above), turbo function, MAF, etc.

I usually get 650 mile tanks in winter and 700+ in summer, and that includes a lot of local driving and time at 75+ MPH. It is possible.

IndigoBlueWagon said:

First, you probably don't have accurate FE data unless you've filled the car several times. Second, automatics will get FE in the 30s when driven reasonably hard. Third, there are an array of things that you should check to make sure your car is running as well as it can, including timing, intake cleanliness (as posted above), turbo function, MAF, etc.

I usually get 650 mile tanks in winter and 700+ in summer, and that includes a lot of local driving and time at 75+ MPH. It is possible.

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Im with IBW on this one. Check those things and your thermostadt. Do your rear brakes drag? If it is in fact an auto you should still be able to achieve low 40's which would put you over 500 miles to a fillup. There seems to be an overboost problem that some cars have that rob mpg's. Do a search and you should get a feel for whats involved with that problem.

In the low 30's with a manual transmission you probably have more than one issue going on.

With my 05 in the summer I regularly get over 700 miles to a tankful, Ive been over 800 miles several times, so it is possible.

It is an automatic, and if it had been just the dealer making that claim and not many people I've read posting on these forums as well, I wouldn't have believed the dealer. Either way, I wasn't expecting to get 50mpg , but much closer to that than I have been.

Thank you for the suggestions, would I be able to take my car to the mechanic and have him check these possible issues for a reasonable cost? I don't know a lot about the mechanics of cars, and if I had the tools, I'd be willing to learn. I don't expect to get the maximum fuel economy, although it would be great, but i was expecting to get over 30 in the city, and over 40 on the highway. What would be an overboost problem?

I appreciate the help, are some of these things I'd be able to try to diagnose myself, or would I need to take into a mechanic?

I'd take it to Jason's TD repair in Oregon. He's a bit of a drive for you (couple hours) but worth it. He knows these cars cold and will diagnose it accurately. He's JasonTDI here.

thanks so much, I'll do that.