You can't go entirely by your halfway mark. I know at least in my car, the second half of the gas gauge goes much faster than the 1st, even if I'm driving the same.
Right now, I'm at 130 miles on a quarter tank. This is all city driving. Definitely won't result in over 500 miles on the tank!
I'm around 3k rpm in my 5-speed at 60. Not sure my mpgs there though. Highway speedlimits down here are usually 65-70 so I'm usually doing 70 or so
But I get close to 30mpg doing 70.
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The Baby:
Darla, 102k, '99 New Beetle GL 5-speed. Bone stock. Acquired 4/6/05. Gave her life for me 8/17/11. RIP
The Project:
Klaus, 180k+, '84 Jetta GL Turbo Diesel. Rebuilt and bringing 50+ mpg. Slightly improved from stock
Acquired 7/12/08
The Baby Brother:
Günther, 20th Anniversary Edition GTI
The money saver:
2001 Jetta TDI GL. 114k. Dead auto, swapped to 3 pedals. Hubby's DD and our trip car