Over the summer, we moved to a new home (on the lake ). I went from a 7 mile commute to an 80 mile commute (each way ). Fortunately it's an 80mph run the whole way. Around this time, as luck would have it, gas prices skyrocketed. I'm now spending about $30/day on gas for my beloved MB. I can't bring myself to part with a nearly perfect MB in favor of a hybrid japanese rollerskate. So, here's my question:

Is there a way to significantly reduce the rpm's at freeway speeds? Either through a lower ratio differential, or regearing the transmission itself. In the case of a lower ratio diff, what's the lowest available and how much effect would it have? Any idea of cost? Obviously low-end torque would go out the window, so can the transmission be modified for 1st gear start?

Car is an 89 300E with 168k on the clock. Oh yes, Donnie Drummond is my mechanic (just lucky I guess). Will give him a ring this week to discuss also.

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