DieselRocks said:
Don't know where you getting numbers but I have 2005 Passat and my average fuel is 33MPG. Most of it is highway 65-70MPH. I fill my tank and at the same station and count my MPG. Did some oil/gas filter maintenance, did I missed something, why it is so low
And your numbers seem about right. 70 MPH doesn't help a car that has never returned stellar MPG, like most vehicles, especially diesels, 55 MPH is the sweet spot.
While it is true lower speeds usually if not always give the best mpgs, it does also matter and have to figured in what the terrain you are driving over along with how you achieve that speed.
Hammering the throttle to achieve desired speed or while going up a grade will lower that number significantly even if you keep your speed down, IE just letting CC hammer the throttle while climbing a grade @ 70- ~75 mph.
I have personal experience with a 04 Passat TDI that is twice a week driven from Denver to Ft Collins on I-25 @ speeds that are the same if not a little faster but never sees below 38-41 mpgs. But the car is driven very easy around town at lower speeds, allowing it shift into the highest gear possible all the time. And it is never hammered to reach or to hold highway speeds when terrain varies, which it does significantly on that twice weekly drive.
The point is that if you drive around in your Passat always hammering it on take off, keeping your foot down not allowing it to shift through the gears to get into high gear with a locked torque converter @ 32-38 mph and similarly always asking for more power on the highway to scream up grades it will always use more fuel...........
I have seen these things achieve well above over 40 tank after tank when in the hands of a driver who puts effort into saving fuel while still driving at what are reality speeds today.
But in the hands of a driver always driving like a peddle pusher, hammering the throttle just to have to slam on the breaks these things can struggle to get out of the high 20s.........
My guess is you are somewhere in-between on that scale
, not a peddle pusher but not really a mizer either. Put some effort into watching the things that waist fuel and I almost guarantee you will see a increase....