From the Aviation Consumer:
Meanwhile, the ultimate in wretched excess, or perfection, depending on your point of view, has to go to the Comanche 400. It was introduced in 1964 and discontinued only a year and 146 airplanes later. This beast had a normally aspirated, fuel- injected, eight-cylinder Lycoming IO-720-A1A fitted with a three-bladed prop. The airframe is essentially identical to the 250, except the 400 uses the Aztec stabilizer.
The engine gulps huge amounts of fuel (20 to 22 GPH at 75 percent cruise, held in optional 130-gallon tanks), has a TBO of 1800 hours and costs north of 50 grand to overhaul. On the other hand, the 400 offers spectacular performance—at least for 1964—with max cruise in the 185-to-195-knot range.
