Not far from Kimberley there’s a long and straight gravel road covered in a thick layer of fine dust. It’s hardly where you expect to see a limousine performing full-bore getaways before running up to typical British motorway speeds and then backing off. However, it proves perfect for testing the rubber seals Bentley has chosen for the Mulsanne’s huge doors.
The next day, under bright blue skies, we head out of Kimberley again for a variety of different tests, including some sustained high-speed runs on surprisingly well maintained bitumen roads. Before we set off, though, there’s a 10-minute briefing to detail the day’s activities and focus attention on a report placed in each of the Mulsanne prototypes.
The first entry into the report is made by Bentley's engineering boss Ulrich Eichhorn even before a wheel is turned. He’s concerned about the ride height on one of the prototypes. “It needs to drop by 5mm,” he says pointing to the space between the Mulsanne’s towering 21-inch wheel and the top edge of the front wheel arch. “It’s not a big problem, it’s just a software fix.”
For the next four hours we pound across the vast reaches of South Africa at speeds of up to 160mph. The Mulsanne devours big distances at high speed with terrific composure and astonishing refinement. There’s an alluring burble to the engine, but it’s always distant and never grows to more than a hushed hum.
When we arrive at a service station to refuel, the digital gauge within the newer of the two Mulsanne prototypes’ instrument binnacles is showing 34deg C – hardly the sort of broiling conditions I expected for a hot-weather test of Crewe’s latest saloon. But as part of its testing procedure, Bentley has already exposed an early example of its new upper luxury saloon to more than a year of sunlight somewhere out in the South African countryside.
Back at the hotel, we reflect on the day’s testing during a formal debrief. I’m genuinely surprised at the detail and thoroughness the Bentley engineers go into as they work through the day’s fault report. There are 8000 parts in the new car, and it’s clear that the team knows each and every one of them intimately.
It’s safe to say that when the Mulsanne goes on sale it will be very well sorted – more than any other Bentley model, thanks to the almost fanatical efforts of Eichhorn and his team. Out here, in this old mining town, it really is a diamond in the rough.