The Porsche Panamera S Hybrid is a great achievement. It delivers sports car pace with near family car economy and emissions. What’s more, the claimed 41.5mpg figure is achievable in the real world, even if you do have to drive carefully to do it. Overall, the Panamera S Hybrid is the finest and most engaging car of its type in the world. But while it’s the best hybrid, the V8 is better to drive, and cheaper.

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.

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Capable of 41.5mpg and emitting only 159g/km 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.

The petrol-electric drivetrain that makes all this possible is largely the same as the one used in the Cayenne S Hybrid – an Audi-sourced 328bhp supercharged 3.0-litre V6 mated to an electric motor with 47bhp. These combine to produce 375bhp, which is only 19bhp less than the Panamera V8.

Unlike that car, the hybrid also gets electric rather than hydraulic power-steering and an eight-speed auto gearbox that sends drive to the rear wheels. Pull away in the Panamera S Hybrid, and the first thing you notice is the silence. In fact, Porsche claims that, in eco mode, the car can run on battery power alone up to 53mph and for 1.25 miles, although we never got close to this distance on our test drive.

You have to be very gentle with the throttle pedal to run on electricity alone, otherwise the engine soon kicks in. Thankfully, when it does, the transition is seamless – and instant thrust is available. It’s also impossible to tell when the engine cuts out again, which it does when you lift off the throttle and coast. This puts the car into ‘sailing mode’, where it freewheels to save fuel and the electric motor recharges the batteries. Applying the brakes also tops up the cells.

In fact, for the most part, all the slowing of the vehicle is done by regenerative braking – it’s only when you press the pedal really hard that the regular calipers actually engage. Make no mistake: the hybrid system is extremely effective. Drive cautiously and you will be able to get close to, and in some cases even surpass, Porsche’s claimed 41.5mpg. In this respect, the Panamera S Hybrid is a real technical achievement.

However, the car won’t suit everyone. It costs £86,476, which is £5,867 more than a V8-powered Panamera S with PDK dual-clutch automatic gearbox. While that car will only do 26.9mpg, you would have to travel about 73,000 miles in the hybrid before recouping the price difference in fuel savings alone!

Admittedly, this figure doesn’t take into account the fact that, with emissions of 247g/km, the V8 would cost more in tax. Nor does it come with the excellent air-suspension that’s standard on the hybrid. But how relevant are such costs, anyway? If you can afford to spend around £80,000 on a Porsche, you can afford to run it. And the V8 is a better Porsche.

It makes a sportier noise than the hybrid and, at 1,800kg, it’s 180kg lighter, so therefore slightly faster and more agile on a challenging road. Its brakes and steering are more user-friendly, too. That doesn’t mean the new model won’t appeal to some people, though. The S Hybrid is a very good grand tourer, which opens up the Panamera to a whole new audience – well heeled individuals who wouldn’t normally consider buying a car as polluting as the V8. And in this respect, it’s a resounding success for Porsche.