I very consistently get 28-31 mpg on the 91 300D. Never seen lower, never seen higher. However, I just used up 4 gallons to go 80 miles....I had never seen the gauge so quickly get to the 3/4 mark.

Could a bad tank of fuel ALONE account for such a deterioration in mileage? There are no other symptoms.

I know I need more data to form firm conclusions....at this point I'm simply wanting to know if bad fuel alone could cause a 30% drop in fuel economy.

Thanks.

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 159k miles
06 E320 CDI "Rutherford", Black on Tan, 179k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 145k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 77k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife