2000 New Beetle TDI 5-Speed. Engine has 197,000 mi on it. Has Greasecar kit on it (not currently used). Story goes from the seller that a husband and wife owned the car, husband purchased and drove it from new to 126,000mi running veggie oil primarily. Then she drove it from 126,000 to 187,000, never running oil. The dealership that sold it to me specializes in Greasecar conversions and such, and they ran a couple of tanks of oil through it, and I've tested it with the oil that was in the tank when I bought it, but haven't gotten my filtration set up to run any more through it. I suspect the lady granny-drove it, which may be related to my problem.
Problem: the car gets about 30-32mpg mixed city/highway over trips of about 10 miles (back and forth to work). On the highway (drove 1000mi to NY recently), got consistently 36-40mpg, maintaining 70mph, only stopping for fuel. Needless to say, this is a bit low from what I expect from a TDI. The car has gotten better than this mpg in the past, maybe 40 city, 50highway, when first purchased, but has declined over the past 10,000mi to the point its at now. Replaced fuel filter, no difference. Regularly run diesel injector cleaner, doesn't seem to make any difference. Doesn't exhibit any symptoms of running poorly, just doesn't get very good gas mileage.
Sort of at a loss here, wondering where I should start in investigating this. Any VAG-com checks I should run, or things to do to try to determine the cause?
Problem: the car gets about 30-32mpg mixed city/highway over trips of about 10 miles (back and forth to work). On the highway (drove 1000mi to NY recently), got consistently 36-40mpg, maintaining 70mph, only stopping for fuel. Needless to say, this is a bit low from what I expect from a TDI. The car has gotten better than this mpg in the past, maybe 40 city, 50highway, when first purchased, but has declined over the past 10,000mi to the point its at now. Replaced fuel filter, no difference. Regularly run diesel injector cleaner, doesn't seem to make any difference. Doesn't exhibit any symptoms of running poorly, just doesn't get very good gas mileage.
Sort of at a loss here, wondering where I should start in investigating this. Any VAG-com checks I should run, or things to do to try to determine the cause?