Swedes press on with all-in-one car pedal

Swedish mechanical engineers are working on a top-secret prototype car that operates using only one pedal.

The revolutionary technology, which combines the brake and accelerator functions, has attracted the attention of Sweden's two famous auto-makers, Saab and Volvo. Both companies are understood to be testing the "uni-pedal" for themselves and to have offered generous grants to the academic institution that has spawned the idea.

The man behind the invention is Dr Sven Gustafsson, a researcher at the Institute of Psychology at the University of Uppsala, who believes the invention will be as significant to the motoring public as the introduction of automatic gearboxes. He has been working on the project since 1994, although only in the last six months have mainstream car manufacturers picked up on the idea.

But having seen the prototype in action, Volvo and Saab, which have both made their names embracing safety technology, have been quick to identify its advantages. Because the foot does not need to leave the pedal between functions, a driver's reaction to danger will be that critical fraction of a second faster.

In fact, testing by engineers has revealed that the time lag for moving between pedals is around 0.2 seconds, representing five metres of extra travel in a car moving at 50 miles per hour.

Although no car manufacturer has come up with the idea before, the mechanics of the pedal are not hugely complicated. The main shaft leads down to a horseshoe-shaped clasp in which the accelerator footplate pivots forwards and back. The accelerator is operated by pushing down the footplate only. To apply the brake, the driver pushes the whole pedal forwards with his leg and the accelerator automatically cuts out. An ankle holder at the back of the pedal prevents the foot slipping off entirely.

Testing of the prototype on a select few members of the public has not yielded the results that Saab and Volvo were hoping for. The main problem has been that drivers have left the accelerator down while braking and not let it up again afterwards. The braking cuts the accelerator out, but when the brake is subsequently let back up, the car lurches forwards violently.

Other problems encountered by test drivers have included leg cramps and overcompensation for the quicker braking mechanism.

Nevertheless, development teams at Saab and Volvo are keen to continue experimenting with the technology, recognising that some of the problems could be ironed out with more work.