At idle my 1985 300TD operates right at 80 degrees as well as when driven up 50 mph. Once I start driving it faster up to 70 ar 75 MPH the temperature moves to between 90 and 100 but it never touched 100 yet. Is this normal? Are these car just supposed to be driven slower? My 1987 260E stays right at 80 degrees if I drive it 90MPH+ for hours. I believe that part of my problem might be that my wheels are not straight (right wheel point slightly right and the left wheel slightly left) and that's causing the extra drag and making the engine work harder and therefore the temperature is higher. I will replace the tie rod assemblies this weekend and hopefully the temp will stay in the eighties.