Ford's twin-turbo V-6: it's all gain, no pain

save for guzzling V-8 oddities like the 555-horse BMW X5 M. This Ford will even out accelerate the Porsche Cayenne S, a smaller S.U.V. whose 385-horsepower V-8 produces a 6.4 second run to 60 m.p.h. All-wheel drive, an option on the base Flex but...