The fuel economy figure is during the test and would be driven markedly downwards by the 'performance' sessions. Thirty mpg plus, a 50% improvement on petrol, would be attainable in real life. The difference under urban conditions would be even more marked - there's a reason why these cars were used as taxis.

And while the 0-60 figure is unimpressive the 40-60 in top isn't that sluggish for the day.

When I first came to live in Spain in 1990, the VW Golf GTD was considered quite a sporty upmarket, almost yuppie sort of car and driving a diesel engined car never had any image issues. As previously mentioned, big lumbering diesel powered Mercedes barges were absolutely standard taxis on most of the continent and, again, still no image problem if the local bank manager or school headmaster drove one.
The same was true of most of the continent, where lower fuel prices and lower tax bands of diesel cars meant that they took off decades before they did in Britain. When I worked part time in a filling station in my mis-spent youth (paying for driving lessons!) the DERV pump was in the "lost" corner of the forecourt, the preserve of truckers and the odd taxi.
Am I right in thinking that Brent produces very little or no fuel for diesel, and that most diesel fuel in the UK is imported? Might have something to do with the slow acceptance of diesel engined cars in Britain.