Here's an update after my trip. Though I haven't had to refill the gas tank yet, given current consumption and current trip odometer readings, I am projecting 24-25 MPG on a 1990 300E with 130000 miles and otherwise bone stock except for the modified cowl. Car was moderately to above moderately loaded and had a/c running the whole 300 mile trip. Improved acceleration at low and high speed. Improved torque available seemed to help downshifting as well.

Don

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Don Drake

1990 300E 125k Miles
1994 S420 100k Miles