Volkswagen Passat

How large an engine do you need in a mid-size car? Just a few years ago, the answer would have been a V-6 of 2.8 to 3.5 liters, perhaps with a base model offering a four of 2.4 to 2.8 liters. Then Hyundai announced in late 2009 that it would abandon V-6 engines altogether for its 2010 Sonata, fitting only fours. The base Sonata engine is a 2.4-liter four putting out 175 hp. But how small can you get? And how many horsepower do you need? Would, say, 160 hp be enough? A 2009 Volkswagen Passat wagon, used as a test bed for "radical downsizing" and shown in Germany by Bosch Mahle Turbo systems...