The 900bhp, all-wheel-drive racing prototype has a top speed of about 210mph, but had to adhere to road speed limits at all times.
The roads were not completely closed, but the Porsche convoy benefited from a rolling road block established by a team of eight Police outriders. London’s Congestion Charge wasn’t an issue because it doesn’t come into force until 0700hrs, besides which the 919 Hybrid isn’t road registered.
Webber completed the runs purely using the 919 Hybrid’s four-cylinder internal combustion engine. Cooling was an issue because the racing car is not designed to be driven so slowly for such a length of time.
“This wasn’t a trivial show car run - I had a few things going on," he said. "The car itself put up a bit of a challenge in terms of being able to go that slowly. The 919 Hybrid is built to be a flying machine and take in a lot of air for cooling. It is fitted with a downforce package specced for 220mph, so to drive it at between 10-15mph for a long period of time was a little bit of a concern. I was tempted to floor it and get into second gear but I had nowhere to go."
Webber said he wasn’t able to take in London’s iconic landmarks during his cruise around the city: “Visibility was tricky, especially when it was dark, although the lights on the Porsche 919 Hybrid are awesome - they are good for 220mph so I didn’t have to worry too much about that.
“The windscreen is essentially cut in half because of the sun shield we need for endurance racing, so I couldn’t see the top of Ben Ben or much of Trafalgar Square, for example. I got a good panoramic view, but I was keen to miss cyclists, traffic lights, junctions and kerbs. The kerbs were a really nasty height for that car so I couldn’t risk touching them.”