First look at a new fuel filter - that'll have a lot to do with bad mpg. Tire pressure while you're at it.

Smoke during acceleration (black smoke) is okay - A LOT of smoke could mean air filter (did you replace it?), another issue that I'm not aware of, or it's just the way your particular car is.

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- Brian


1989 500SEL Euro
1966 250SE Cabriolet
1958 BMW Isetta 600