Brian, yes, the '85 has taller gearing. The '84 and earlier turbos have 3.07 rear end gears, but in '85 they switched (on both the 123 and 126) to 2.88 gears. I'm turning 3000 RPM at 70mph; 65 is a bit lower but I don't remember the exact number (I usually cruise right at 70, unless, as mentioned, the car starts creeping up in speed). According to the shift dots (I haven't actually done this), the car can get up almost to 75mph in 3rd gear! I got the car up to 80 or so when driving back from Texas (bought the car there; federal emissions is a good thing), and she had plenty more to go...I was just too chicken to risk getting the ticket.

Tom, I think that your question is subject to opinions. The 300SDL uses a 6 cylinder engine that has an aluminum head mated to a cast-iron block. This doesn't concern some people, but I refuse to take the risk of the head expanding at a different rate from the block and eventually warping the head and blowing the head gasket, particularly if the car's overheated. Other than that, I don't think there are any reliability issues with the 3.0l OM603, but I'm not sure either way; again, the head issue was enough to turn me off to the idea in the beginning (this is also why I have an M-B instead of a VW).

That aside, IMHO the 126 and the 123 are both excellent chassis, although the 126 is more technologically advanced...meaning it's both more comfortable and there are more parts to break. This is really a matter of personal preference. If you want a car that's rock-solid reliable but don't care for creature comforts, the real way to go is a 123 240D (or Euro 300D) with a 4 speed manual transmission, manual heater/ac (if equipped) controls, hand-crank windows, manual sunroof, etc.