My 2003 TDI ALH used to get around 50+MPG while running 16" tires 205/55/16 in the beginning but gradually dropping about 6 years ago. It's been running 17" for 3 years now with 225/45/17 tires for 2 years and I upgraded it to one size up to 225/50/17 last year. I take it to my cabin in the wood often, need the extra clearance, added bug deflector and occasionally have roof rack with fairing on but it's only getting around 37-41MPG . Sometimes I can get 45-46MPG all highway. But nowhere near what it used to get. I'm hoping to get at least 45-46MPG with mixed driving while keeping my 17" setup if possible. I rarely run AC/Heater but when I need it usually only run for couple minutes to get to temp and open cabin recirculation.
This car gets regular scheduled maintenance like timing belt, air filter, fuel filter, oil change, etc. No mod done on this car, everything is stock.
Currently it's got 265,405miles and it just got new set of brake pads and rotors all around and new rear calipers.
I attached some charts from group 003, 011 and 013 to see if an expert can see something. To me it looks normal. I was looking to replace the original MAF, maybe it's dirty but I don't see anything wrong from the chart. Oh yeah, no CEL on dashboard . I’ll be replacing all the vacuum hoses with silicon one soon.
What kind of tune up would you recommend to improve my MPG while keeping 17" tires?
11 years of MPG datas