3.5L DOHC V-6 (Lincoln MKZ)

263 hp/249 lb.-ft.

+ Plucky midrange

- Economy good only compared with V-8

= Fine high-volume effort

4.6L SOHC V-8 (Mustang Shelby GT)

319 hp/330 lb.-ft.

+ Brawny; exhaust note to die for

- We’d still like a few more revs

= Practically perfect muscle-car motor