Brands show off smart tech

The stunning petrol-electric 918 Spyder has just set a new record on the Nurburgring.

Cleaner air and smarter technology were hot topics at the Frankfurt motor show this year, with a fast-growing number of makers showing their contribution to the environment via reduced exhaust emissions. Mercedes had a big new S-Class 500 sedan with hybrid power that could get to 100km/h in 5.5 seconds - and return 3.0litres/100km - and also had an Intelligent Drive version that meant it was capable of self-driving.

Mercedes proved its ability with the technology by sending the car on a 100km+ run, twisty roads included, with no human intervention or control -- tracing the steps of the first car journey ever taken, by Bertha Benz in what was then her husband's new invention.

The car was also programmed to stop and pick up people waiting at bus stops, but Mercedes suggested that more improvements are on the way. "It's not perfect yet," a spokesman for the brand said. "(At the moment) if the person does not move, neither will the car."

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Most of the green cars at the show touted their environmental data on their bodies. Citroen had a DS5 with Hybrid 4 drivetrain that coughed just 88g of CO2/km into the atmosphere, but Toyota had an Auris (Corolla) hybrid sport with an 85g reading and Peugeot produced a 208 hybrid that could run to 100km/h in eight seconds and emit 49g/km.

VW introduced its e-Up electric car and a battery-powered Golf, and made it clear it was focusing on those drivetrains for up to 40 future models. And even Porsche had a hybrid on show -- the stunning petrol-electric 918 Spyder that has just set a new record on the Nurburgring.