Stop-start? Is the Mini doing a little bit of Prius copying?
Sort of. Stop-start systems are nothing new (manufacturers have been experimenting for decades) but they certainly have been made fashionable by the hybrid gang, led by the Toyota Prius and Honda Civic Hybrid. It's a simple premise: when stationary, there's no need for thirsty petrol engines to be running. The latest stop-start systems cut the engine in traffic jams and at red lights, restarting the instant you depress the clutch. End result? Fuel and emissions savings of around 9 percent. It's a rapidly expanding trend and you can expect around a third of all new cars to have stop-start by 2012. The BMW group is gradually rolling it out across its range, and the first new Minis with the tech are rolling into showrooms this week. Click 'Next' to see if it's as good in practice as in theory.
How does the new Mini's stop-start system work?
Once the engine is up to full operating temperature, the car is programmed to cut the engine when you're at standstill with the transmission in neutral (those used to staying in gear at lights won't get the system to work). A beefed-up, faster-acting starter will then wake the engine the instant you depress the clutch to select gear and move away. That's the idea, and it works well in practice; the 1.6 restarts immediately and you're never left waiting impatiently, even if you're doing a tyre-burning getaway. You must adapt your driving style and select neutral every time you come to a stop for the engine to cut, and once it does you're left in eery silence. The air-con and stereo functions continue to work (although air flow rate is less powerful) and the only telltale sign that you haven't stalled is a flashing stop-start symbol winking in the messages display. There's nothing complicated to befuddle Luddites. If you're working on a tan and enjoy global warming, or if the system has a fault, you can push the button near the gearlever to turn the stop-start system off. But we can't think why you'd want to. It's a simple technology that works seamlessly in the background, and you'll save money by letting it do its thing. Of course, it's not just stop-start - there's a whole suite of BMW's Efficient Dynamics working in the background on new Minis built since August 2007. The alternator only charges the battery when necessary, decoupling when not needed to avoid sapping power, and Switch Point Display advises the driver when to change up.
So how much fuel will I save?
Depends on the strength of your Mini. The cleanest, the new PSA-powered diesel, will produce a Prius-equalling 104g/km of CO2 and sup a gallon of fuel every 74 miles - it's nearly teetotal in car terms (previous diesel 118g/km and 64mpg). The Cooper S we drove now averages 149g/km and 46mpg (down from 164g/km and 41mpg). Of course, these figures are obtained in the lab - back in the real world, you'll have to work hard to match those figures. Especially drivers who don't naturally leave the car in neutral when stationary. But there's much to applaud here. You don't need the engine to be wasting fuel at standstill, and with stop-start you enjoy the hybrid-like halo effect of tranquility in traffic jams while all those around you noisily spew out exhaust fumes. And the moment you set off, you'll enjoy all the usual Mini attributes of pointy handling, quality build and zesty performance in the Cooper S (for a full road test, click here). If this is a taste of the future, bring it on.