Engine testing until breaking - 60 years ago.

[nielshm]

Now thats funny.... 

Driven with a average of more than "1 mile pr. minute" engines normally only lasts until 20.000 miles. So a little convoy sets off to the autobahn in Germany, and drives ud and down until they reach 20.000 miles. 10 min. teatime is required every time they stop for fuel, so the hightech masterpiece in front of the brilliant BMC car is'nt stessed out. 

[Gerg]

In one of the shots I think I saw a car's speedo reading 80 mph.  A Morris Minor 948cc (one of those cars in the film) had a top speed of 75 mph, so quite demanding for 1956.  The Morris Minor looks like its almost ready to take off in some of the motorway footage.  Lever arm shock absorbers!

[FROSTYBALLS]

Actually taken to 25,000 miles. 

Manufacturers continue to do loads of testing on public roads nowadays. Toyota have been testing the Corolla on UK roads for example.

Back in the early 80's, BL had modified VW Jettas running around Birmingham - testing the A-series engine with the VW gearbox. They had a massive bulge in the bonnet to allow space for the different engine/transmission combination, so were easily recognisible.

Not living far from the JLR plant at Castle Bromwich, we often see various prototypes of their vehicles, albeit with abstract paintjobs to disguise features.