Winterized diesel would also account for some of this. Half tank is not the most accurate either. I have not checked mine lately, but it seems like it is averaging just under 30, mixed city, rural and some longer runs at 65 - 70 mph.

Is all the general maintenance good? Synthetic oil, tranny fluid, rear diff, tire pressures (mine are about 40psi), filters (air, gas - pre & main), would like to think with the miles you have you should not have problems with wheel bearings, yet.

Oh, in weather like this do you have the A/C off? Basically it is always on unless it is in Economy mode, that would account for a couple mpg there.

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raMBow

1999 E300DT Obsydian Black Metallic, Heated Full Leather Parchment options, E2, K2, 136,000+, best 36.5 mpg - GP's 12-04 & 11-12 Zero Stuck
2010 Honda Odyssey - The BrideMobile - best 26.5
(2) 2005 Honday Accord- (1 -Corporate 1 - Personal) - 110,000 4-cyl 30mpg
2000 VW Golf GLS TDI, Upsolute Chip (sold to Brother, now 300+k on it) 48.5 mpg like clock work
1987 Honda CRX HF - Sold 87,000 always over 50 mpg Max 67 mpg