Cruising RPM at 60mph of 89 Mercedes 190E 2.6 auto Mine running at 3000 - unsure if OD working or not?
There's nothing wrong--your 190E 2.6 auto does not have an
overdrive. The transmission's top (4th) gear is a 1.00:1 ratio. The
2.6 cruises at 2900-3000 rpm at 60 mph naturally. You still should
be getting around 28 mpg. There are 5sp-manual conversions, and you
may even be able to convert to a later Mercedes 5sp automatic with
some work, which would certainly lower your cruising speed rpm.
This would probably end up being cost-prohibitive, however.