Ellise Shafer When the news came out in December that “The Grand Tour” — Jeremy Clarkson, James May and Richard Hammond’s post-“Top Gear” automotive series — would be coming to an end, fans were left wondering why. But, in a new interview with The Times, Clarkson has delivered a cheeky yet straightforward answer: it’s because he’s “unfit and fat and old.” Clarkson told The Times that the show “is immensely physical, and when you’re unfit and fat and old, which I am…” He also feels the trio has done just about “everything you can do with a car.” “I’ve driven cars higher than anyone else and further north than anyone else,” Clarkson said.