Sherwood, actually the Murano is not at all a version of FX. The Murano is based on Altima FWD platfrom, while the FX is based on G35 platform. Besides that, the Murano is more practical as an SUV, while the FX is a sporty cross over. Completely different vehicles.

As far as built quality, both Nissan and Infiniti suffered from cheap materials and lousy assembly, and most of Nissan models still do. However Nissan has done a great job to improve Maximas and Altimas interiors, and the new Infiniti M and G have awesome interiors.