It wasn’t that long ago that the idea of a front-wheel-drive Mercedes-Benz would have been sacrilegious to fans of the brand. True luxury-brand cars were supposed to have rear-wheel drive, and while the Japanese brands — like Acura and Infiniti — began to change some of those perceptions, the Germans steadfastly stood their ground. But you can’t hold back the tide forever, and after Audi survived its foray into front-drive cars, Mercedes-Benz and BMW eventually gave in and started coming up with front-wheel-drive models of their own. The cars slot into entry-level positions in the automakers’ lineups at relative bargain prices, allowing new generations of buyers to get into a luxury brand earlier in life.