Usually, a carmaker debuts its latest ride by driving it onto a stage, the spectacle of the event underscored with smoke, strobe lights, and clean-versions of trap music hits. Jaguar, on the other hand, rolled out its new XF sedan by actually rolling it - very, very slowly - across a tightrope spanning London’s famous River Thames. Not since Shackleton’s icy expedition has such a feat of daring been undertaken by the swashbuckling Brits! Or, at least, it’s a better stunt than the smoke-and-mirrors discotheque show we’re used to. Without spoiling anything explicitly, we will say that the Jaguar crossed the river without soiling its parchment leather or burled walnut trim.