The Cozy Mark IV is in a class by itself. It is the most popular plans-built, high-performance, 4-place. Its safety record is unexcelled. Building cost at $15,000 for the airframe is about one-half that of prefab 4-place designs, and building time is about the same. With a useful load of 1000 lbs. a range of over 1000 miles, and a speed of over 200 mph, it has equal or better performance and utility than factory-builts costing $250,000 and more. The Cozy Mark IV plans and instructions are the most detailed and complete of any design on the market, and builder support is unequalled.

The Cozy Mark IV has the reputation of the most thoroughly flight-tested experimental design. Aft c.g. flight testing was done by ex NASA test pilot James Patton, and reported in April '94 Sport Aviation. He concluded that a Cozy Mark IV, built according to plans and operated in the approved c.g. range, has excellent stall resistance.

Ed Kolano, test pilot for Sport Aviation, gave an excellent evaluation of the Cozy's flying qualities in November '98 Sport Aviation. He concluded, "It is comfortable and boasts impressive performance numbers. It has benign stall characteristics and positive dynamic stability and it is easy to fly."

The CAFE Foundation's excellent evaluation of the Cozy's performance was reported in April '99 Sport Aviation. It concluded, "Its cross country efficiency places it among the top homebuilts in its class."

Co-Z Development pioneered the concept of a side-by-side configuration of the Long EZ back in 1982, and is the only such design licensed by Burt Rutan.