2010 Maserati GranCabrio

If there’s a slowdown in the auto market and a shift in the public’s focus from mph to mpg, it won’t be reflected at the Frankfurt auto show. To a roster of debuts already boasting a pair of poster-worthy Porsche debutantes and a duo of 450-plus-hp BMW hybrids, Maserati is adding its newest model, the 433-hp 2010 GranCabrio.Based on the scintillating GranTurismo, the four-seat GranCabrio