I've owned two 380SE cars. Both 1985, one was a US spec car with 200K+ on the non-working odometer when it was totaled out by a side impact.
The other a euro 380SE which I still own, would not call slow and at 200K miles it still does 20-22mpg.
Look for records of timing chain tensioner replacement and oil changes.
Run from any "ticking" sound or rough running ones. Cams will go flat if oil changes have not been done properly. Otherwise, they will run as long as a diesel.