My experience with my two Rovers, both Series 1s
1999 Disco Series 1 with 113,000 miles, owned since new.
1997 Disco Series 1 with 117,000 miles, owned since 74,500 miles.
List of problems
1. Rear diff break, removed driveshaft and axles then drive 750 miles home.
2. Power steering box leak, replaced under warranty (1999).
3. Water pump (1999)
4. Alternator (1997)
5. Wheel bearings (1997 & 1999)
6. Catalytic Converter (1999)
7. Misc seals
I have not had to do head gasket yet.
They have never died and left me stranded.
If I average the 113,000 miles on the 1999, I gets 14.5 average mpg over its total life (yes, I am a record keeper)
If I drive 55mph on the flat road of Kansas, I will get 18mpg.