2016 Porsche Cayenne vs BMW X5

What's the difference?

The Porsche Cayenne is a whopper. It's a big, heavy SUV with tons of room for the family and a badge to keep the neighbours talking. It's also got a planet-bending V8 diesel engine and an air-suspended chassis that has to be felt to be believed.

Richard Berry road tests and reviews the 2016 BMW X5 xDrive40e with specs, fuel consumption and verdict at its Australian launch.

Do you know why we haven't walked on the moon since Christmas, 1972? No deadline, that's why. “Oh the moon's not going away we can go there whenever...” you say. Wrong! Just like this road test, nothing happens without deadlines, including the small steps to save the world like BMW's first plug-in hybrid SUV, the X5 xDrive40e.

At the launch of the X5 xDrive40e in April this year BMW's executives freely admitted that without this hybrid and others like the 330e sedan there'd be no way they could meet the hard-core emission target Europe will bring in for carmakers. The emission deadline: The year 2020. Fail and they'll be fined, heavily. That's how things get done. And that's why you can now gorge yourself on a big, fat 2.2 tonne luxury SUV that can glide silently to work and back on electricity. Sure the electric power runs out after 30km but don't most of us live within 15 kays of where we work? That's what the Department of Infrastructure says.

There's only one grade of xDrive40e, it sits towards the top of the X5 line-up and it's a match in price and specs for its xDrive40d diesel brother. That emission deadline doesn't just have Bimmer under the pump, Mercedes-Benz has just launched its hybrid rival to xDrive40e, the GLE 500e and Audi has its Q7 e-tron on the way.