In the past, Chrysler has temporarily restored its fortunes by conjuring up a sizzling new model just when it most needed one. It more or less invented the minivan in the 1980s, and the “gangsta”-style 300, launched in 2004, restored America's appetite for big saloons. There is buzz around the new Dodge Challenger, but the tyre-burning coupé will not generate enough sales on its own to make a difference.