To say it is a 'Mustang' chassis in misleading, you could also call it a Lincoln LS chassis. Several vehicles have been designed by Ford engineers from a basic chassis, none of which are similar overall. The Current RWD Mustang chassis is a derivative of the same basic chassis on which the Jaguar S, the Lincoln LS and the T-Bird were derived. That chassis, like any other chassis it can be stretched, shortened, widened or whatever, on which to build totally different vehicles. The 2008 AWD full-size Lincoln MKS with a 4.4L V6 that get 30 mpg, for example, is a derivative of a chassis from which several Ford and Volvo, distinctly differ models were derived, as well. By using a basic chassis a manufacturer can save billions in R&D, assembly plant modifications, certifying and meeting government standards then if they developed a 'new' chassis..
mike