I own 4 Mercedes with the M110 engines & have travelled ~ 400,000 miles with them. The CIS system has rock solid & rarely needs adjustment. Incredible cars with a 5 speed trans & I get ~ 27 mpg with plenty of power for another older design car. Engine parts aren't an issue or expensive. I recently rebuilt an engine using factory Mercedes Bearings/ pistons etc. I've never owned a diesel anything & don't have any desire, but that's just my preference. Just the same as some people like diesel trucks.A stock M110 running well is a sweet sounding engine. Same CIS system used as in my 73 911 with no issues after owning for the past 29 years.

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80 280TE, 5 speed
83 280TE- 5 spd, 16.5mm rear sway
85 280SL- 15" Bundts