j_nickels
Member
So my 2004 Golf TDI 5 speed manual gets poor fuel mileage. I drive for good mileage-with the occasional burst to clear out the cobwebs. I'd say on average 60% of driving is city with the rest freeway. And without having my fuel log in front of me, the overall MPG is probably about 33-34. I've run mostly on ULSD from Arco, but have put other "name brand" diesel in when on the road. I'm taking her in to the dealer because I paid quite a premium for this car. TDI's are not sold new in California so dealers can jack up the price, plus I paid for CPO to get that extra couple of years of warranty. I'd like to think there's a point below which low mileage is unacceptable.
My question is, all user-variables and weather being equal, what factors affect mileage, in order of importance. I mean given two TDI's of the same model and year, assuming the weather is the same, speed is constant, tire pressures are identical, the same fuel is used etc, why would one get significantly better mileage that the other? What factors about the car itself have the biggest impact on mileage? I ask in part so that I can go into the dealer armed with information. I had a coolant loss problem last year and I had to take the car in 4 times before they nailed the problem, but only after I had mentioned some of the possible causes that I had learned of here in the forums. I have little faith in my dealer and I don't think they get many TDI's in, but I paid for a warranty so I'm gonna use it. They did a poor job during my last service--the air filter wasn't installed correctly! Part of the seal was totally mangled and hanging over the outside edge of the airbox. I think enough of the seal was intact that no unfiltered air was getting in, but this ruined my faith. If I can go in with a list of things they ought to check or at least be aware of, I'm hoping this will improve my chances of not hearing them say "oh, user mileage varies, sorry we can't do a thing".
I've changed the fuel and air filters myself with no impact on mileage. Beyond this, I don't have the means to do much else. I suppose I could replace the MAF in case that's part of the problem. But what about timing, compression, the injectors, the ecu and what else? Ok, thanks much.
My question is, all user-variables and weather being equal, what factors affect mileage, in order of importance. I mean given two TDI's of the same model and year, assuming the weather is the same, speed is constant, tire pressures are identical, the same fuel is used etc, why would one get significantly better mileage that the other? What factors about the car itself have the biggest impact on mileage? I ask in part so that I can go into the dealer armed with information. I had a coolant loss problem last year and I had to take the car in 4 times before they nailed the problem, but only after I had mentioned some of the possible causes that I had learned of here in the forums. I have little faith in my dealer and I don't think they get many TDI's in, but I paid for a warranty so I'm gonna use it. They did a poor job during my last service--the air filter wasn't installed correctly! Part of the seal was totally mangled and hanging over the outside edge of the airbox. I think enough of the seal was intact that no unfiltered air was getting in, but this ruined my faith. If I can go in with a list of things they ought to check or at least be aware of, I'm hoping this will improve my chances of not hearing them say "oh, user mileage varies, sorry we can't do a thing".
I've changed the fuel and air filters myself with no impact on mileage. Beyond this, I don't have the means to do much else. I suppose I could replace the MAF in case that's part of the problem. But what about timing, compression, the injectors, the ecu and what else? Ok, thanks much.
). So drive with the wind.