Full review: br It's a car that's broken new ground in more ways than one. Not only is the Porsche Panamera the firm's first four-door grand tourer, but now, with the introduction of the Panamera S Hybrid, it's also the most fuel-efficient model the firm has ever produced.br br Capable of 41.5mpg and emitting only 159gkm of CO2, this Panamera is -- unbelievably -- more economical and cleaner than a VW Passat 1.8 TSI petrol. Yet it still delivers the kind of performance you'd expect from a Porsche. It can sprint from 0-62mph in only six seconds, while top speed is 167mph.