The biggest announcement at this year’s Tokyo Motor Show—now called the Japan Mobility Show—might be the new Corolla concept, the new Subaru WRX STI hatchback, or several new Lexus LS variants. In addition, though, there was something even bigger: a whole new brand from Toyota, the biggest automaker in the world. The brand is Century, and Toyota’s ambition for it, as was the case with Lexus before it, is to take on the Europeans at a game they’ve been winning for decades. But instead of Mercedes and BMW, Toyota is going after two marques whose market position has, historically, been even more unbreachable: Bentley and Rolls-Royce. The audacity is thrilling because, on paper, Toyota doesn’t stand much of a chance. Even Mercedes tried to take on Bentley and Rolls by reviving Maybach, before settling instead for a distant third-place in the ultra-luxury wars. Aston Martin likes to pretend it’s in the same league, too, despite being more of a sports-car brand...