At the Geneva Motor Show this week a number of car-makers, including BMW, Daihatsu, Lotus and others, either showed or talked about cars equipped with start-stop systems to help improve fuel economy and emissions. Basically, the idea of start-stop is give some of the benefit of a hybrid at minimal cost, by shutting off the internal combustion engine whenever the vehicle comes to a stop, and then re-starting as soon as the brake is released. The manufacturers of the systems that were displayed were Valeo and Bosch.

The Bosch system goes into production this month and will be installed on the updated BMW 1-series. The Bosch system basically consists of a beefed up starter motor, along with some electronic control that monitors, the accelerator, brake and clutch positions and the battery voltage. If the battery voltage is too low, the system disables, but otherwise functions to improve mileage up to eight percent in urban driving. Obviously highway driving will be unaffected, but that's not a bad improvement for a system that requires no other changes to the drive-train.

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• BMW will use the Bosch start-stop system on updated 1-series

[Source: Robert Bosch GmbH]

Starting this month Robert Bosch GmbH will begin supplying a new start-stop system to BMW for installation on the updated 1-series. BMW will be selling a variety of efficiency enhancing technologies under the brand EfficientDynamics, that will be standard on the 1-series and include the start-stop system and regenerative braking. The start-stop system uses a modified starter motor that Bosch is calling a Smart Starter-Motor.

The new starter has been beefed up to handle the significantly increased number of starts it will have to make over the life of the vehicle and also improve the performance. The system provides some of the benefit of a full-on hybrid at a significantly lower cost. The new ECE15 driving cycle test requires twelve stops of fifteen seconds over a 4.3 mile distance, and the start-stop system helps reduce fuel consumption and CO2 output by up to eight percent. It's not a lot but for a fairly minimal cost, it's a lot of benefit. Longer stops will result in more engine off time and proportionally greater savings. The only question is how smoothly the system will operate, which hopefully will be significantly better than BMW's SMG transmission. If it's not too jerky it could be a very useful system from a cost-benefit standpoint.

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