Respectfully disagree with your post. 3,000 is not going to do any harm to the engine, nor would 3,500 or even 4,000 rpm. He can drive the car all day at those speeds with no ill effects. It will be loud though.

The overdrive on my M46 stopped working over 10 years ago. My mechanic looked into it and told me that I needed a new solenoid and some other OD service (car had over 200k at the time). I decided not to bother with the expense. I have a 3.31 rear end in my car, so the revs are lower, but I drive at 75-80 mph in 4th gear on a regular basis. That is about 3700-4000 rpm. Been doing it for over 150,000 miles and the engine runs just fine. My gas mileage is only a couple mpg lower than it was when the OD worked. Biggest difference is the engine noise in the cabin. I just turn the radio up.