Americans often speak of the $100 hamburger, the food of choice at some airport café a Cessna hour away from one’s home base. The trip to eat and return often accounts for that sum, with avgas stretching toward $6.00 per gallon. Imagine, then, making a coast-to-coast trip across one’s native land, surveying a dazzling array of scenic delights and partaking of French cuisine along the way – all for not quite that amount. Europe abounds in small, turbocharged Diesel automobiles, sometimes zippy little things that exhibit excellent fuel economy. Many of these cars strive for the “3-liter” designation – the ability to drive 100 kilometers (62 miles) on three liters of fuel (78.4 miles per gallon) and the European Union is pushing toward 95 grams of CO2 emissions per kilometer by 2020. Serge Pennec has built several airplanes using these torquey engines, creating a means of traversing distances cheaply and as greenly as possible. Diesels consume their heavier fuel more frugally than …