So surprise number one is out of the bag – maybe Geneva 2010’s biggest. Porsche wasn’t expected at VW’s group preview night at all, let alone to turn up with a new flagship supercar: a car that previews a hybrid-electric replacement for the Carrera GT. A car that, if the show-goers approve, Stuttgart stands ready to productionise, says boss Michael Macht.

This 918 Spyder is quite something. When it drove down the long show stand, I took one look at the front end and thought: “ah, here comes that sub-Boxster model we’ve been expecting.” This car looks that small from the front. Wasn’t until it had coasted down in front of me that I realised the full size of the thing, saw the styling references to the Carrera GT, and finally twigged what I was looking at.

Porsche 918 Spyder eco concept

And here are the facts that I can’t quite reconcile. This thing’s got a 500bhp V8 that revs to 9200rpm: a development of the RS Spyder’s 3.4-litre racing engine, basically. It’s faster around the Nordschliefe than the Carrera GT: faster than 7min 30sec. 0-62mph in 3.2sec, 198mph plus. And yet because it’s got 218bhp of electrical power too, coming from a fluid-cooled lithium ion battery sandwiched between the passenger cell and the engine, it’ll return 94mpg and emit just 70g/km of CO2 on the New European Driving Cycle test.

Because it’s a plug-in hybrid, that low-CO2 performance only comes in ‘economy mode’, and only after a full mains charge, presumably. Even so, that’s incredible from a car with a racing V8. And very clever – slightly disingenuous even – from Porsche. Because you can bet your deposit that it won’t do 94mpg and 7min 30sec on the same lap.

Still, credit where it’s due: Porsche’s pulled off a proper show coup here of the kind that I’ve certainly never seen before. There’s a real buzz to Geneva now. Nobody saw this coming.