Car-sleeper

More fast trains between England and Scotland, and additional "car-sleeper" overnight services for motorists, are important features of British Railways summer timetables, which come into operation on June 17. In all, 98 long-distance trains will be speeded-up to save 10-75 min. and many will make non-stop runs at an average speed of 60 m.p.h. or more.

Source: wiktionary

The Car-Sleeper is a British Railways ingenuity that has caught the Continental fancy. The convenience of the car for the short-distance journey is undeniable—but not so its comfort and relaxation for the long haul. The Car-Sleeper doesn't attempt to challenge the car's attractions for the start of the journey or its usefulness at destination; but it relieves driver and passengers of the strain of a gruelling long-distance drive, [...].

Source: wiktionary