Maybe so SLO but a car broker who made a successful business model worked on the premise that for every ten buyers looking for a second hand car eight would choose a Golf !

I suspect that 8 out of ten is gradually dwindling as VW's cost cutting bears fruit. People are discovering that Golfs from the last 15-20 years are just cars and not worth the premium.

In the 1980s I used a company diesel Golf to collect components from a supplier, the Golf was a left hand drive one which was being used to develop a turbocharger suitable for small diesel engines.

It certainly went well, surprisingly quick on Pennine hills and the M1.

The company I worked for decided not to aim for the passenger car market, though AFAIK supplies the turbo for the Dodge Ram diesel pickup (as well as other Cummins engines.)

Holset?

Indeed so: bought by Cummins in 1972, but convinced existing customers Volvo, Scania etc that their secrets were safe and continued to receive engines to test for matching purposes.

For variable geometry turbos the first customer was Iveco, I think.