A 2015 Audi R18 E-Tron Quattro from the automaker’s penultimate year in the top class at the 24 Hours of Le Mans is up for sale at London dealership Joe Macari. No price is listed, so if you have to ask, well, you know the rest. Audi used the R18 name for a series of race cars from the 2011 to 2016 seasons, after which the automaker ended its Le…