The Quad 4 was once hailed as the powerplant of the future, having the power of a V-8 while the effeciancy of a 4 cylinder. It turned out to be a problematic engine. Before GM worked out the issues with head-gaskets, the ignition system, and other misc. problems the engine had already earned a bad reputation. This is especially because of the single-overhead-cam version, which used a horrible amalgamation of parts and was the worst version of this engine ever made.
The shining redeption of the Quad 4 was its potential as a FWD performance powerplant. It helped Oldsmobile win many SCCA SOLO2 and ISMA competitions, and set a land speed record in the early 90's with the Oldsmobile Areotech. Many hot rodders and tuners thus choose to use the quad 4 because of its potential.