Mazda Ryuga concept vehicle unveiling at the 100th anniversary of the Detroit auto show (NAIAS.) The Mazda Ryuga – Japanese for gracious flow concept was shown at the 2007 North American International Auto Show in Detroit. The Gull-winged Ryuga 2.5-liter flex fuel engine and a 6-speed automatic transmission the best-looking thing at the Detroit show by Mazda’s new chief designer Laurens van den Acker: