Officially called "Auto Start/Stop," the system automatically switches off the engine when the car comes to a standstill. As soon as the driver puts in the clutch or depresses the gas pedal, the engine restarts automatically. BMW's "Intelligent Software" links together the various sensors required with the starter motor and the alternator control to make the process work.
Auto Start/Stop, along with BMW's High Precision Injection (lean-burn direct injection) and Brake Energy Regeneration technologies, will appear across a broad model range, with the Start/Stop technology to be introduced in four- and six-cylinder 1-, 3- and 5-Series models.
[Sources: BMW, Autocar]












Reader Comments (Page 1 of 4)
Ryan @ May 23rd 2006 2:40PM
"stop-start system"
-I love BMW they call it for what it is.
GM on the otherhand,
this is a HYBRID!!! Yeah, bullshit.
Alex Nunez @ May 23rd 2006 2:44PM
This sounds about as cool as Chevy's 1st-to-4th shift thing on the Corvette.
You would thing there's a way to be efficient and not be annoying. I'm sure the tech that ties this all together is very innovative but I'm sorry, this would drive me insane.
Nick @ May 23rd 2006 2:47PM
It sounds like an excellent idea, but don't most engines blow more gas through the exhaust while starting than they would sitting at idle for 15-30 seconds? If I'm wrong, then I wish them the best, but it also sounds like a huge load to be placing on the starter, especially if you live in a city with a lot of stop and go traffic.
pavster @ May 23rd 2006 2:53PM
I wish all cars did this -- such a waste to have the engine running while waiting for a minute at the light, especially a big displacement engine that takes a ton of gas to keep itself running.
Yes, it's a load on the starter, but I'll bet they will be using their intelligent alternator to start the engine; I think Saturn or maybe even all of GM was also taking about doing it. So it becomes more like a gas golf cart. Start the engine only when you actually need it to propell you. Brilliant!
Michael Karesh @ May 23rd 2006 2:57PM
This is hardly the same system that GM calls a hybrid. Anything GM calls a hybrid includes at least regenerative braking and accleration assistance from an electric motor/generator. The simplest are like the system Honda uses, the more complicated go a step beyond Toyota in overall system design (though Toyota might lead in the refinement of the varioud components).
VW had a model that did this sort of thing back in the 1980s. Hybrids do it today.
With a quiet-idling engine and good starter, you don't even notice the engine turning on and off. I also suspect that the conventional wisdom that it takes a lot of extra gas to start an engine dates from the days of carburetors. With fuel injection the penalty is probably much smaller, especially with an engine that is already warm and that the FI computer knows is already warm.
Jim P. @ May 23rd 2006 2:59PM
wow, another gadget to go amiss. Would be a bummer for this thing to quit in the middle of rush hour traffic. And noting that the German cars aren't known for their electronics reliability, I'd rather just have my car quietly idle at the light. Besides, unless your revving the motor when your stopped, the amount of fuel that you're burning is very small. This is just a marketing gimmick.
MikeW @ May 23rd 2006 3:13PM
If your engine idles @ 600 rpm, and the starter cranks @ 60 rpm (The throttle is closed for both) Starting uses 1/10 the gas per time (okay 1/7.5 because of starting enrichment) and it may only take 3 cylinders of firing to start a 6 cylinder engine, so 1 second and it is spinning.
Seems odd coming from BMW, as they have valvetronic, and got ZF to add SBC to the ZF 6 speed autos
Pastulio @ May 23rd 2006 3:15PM
What? It doesn't work through Idrive menu? WHY?
Howard Kerr @ May 23rd 2006 3:15PM
Naysayers, notwithstanding. I wonder if this system will be adapted at some point to the company's V8, to help them avoid the gas-guzzler tax? Nay.
As has been noted by Mr. Karesh, VW had this system in several models in the '80s....I wonder what happened to it? What's old is new again.
Eric L. @ May 23rd 2006 3:19PM
Gas driven golf carts have a delay after you step on the gas before they get going. Hybrids have an electric motor that kicks in to get you giong before the engine actually starts. I wonder how BMW will eliminate the delay caused by the engine starting. Perhaps as soon as you lift off the brake pedal, the engine starts. That should be enough time for a smooth transition.
Carster @ May 23rd 2006 3:22PM
Call me weird but I hope that this does not kill the engine when the car is locked up then... I dont see what the purpose of this is besides an attempt to make the punlic happy. It sounds like a waist of Research and Development. While many of the poeple that can afford the nicest of BMW's would not choose flying coach on an airliner if they could choose a private chartered jet, the same idea is at hand!
jas28 @ May 23rd 2006 4:01PM
This system, assuming it functions like the others in the auto industry that are about to go into production, will start the engine using the alternator as a motor/generator. There should be gas savings (probably 5% at best) which is big to engineers, but small to the public because 5 % of 20 mpg is only 1 mpg, not too noticable to the end consumer. When it's coupled with other savings (mass reduction, cylinder deactivation, such as what GM does, etc.), it does show a good improvement in fuel economy.
Gordon Mackenzie @ May 23rd 2006 4:06PM
pff...Citroen has offered this on the C2 and C3 for years. Literally, 2 or 3 years.
Steve C. @ May 23rd 2006 4:13PM
Let me tell you how dumb this system is. My Accord Hybrid has a stop-start system and it turns the engine off at about 5 mph as you are braking to a stop, even if you never really come to a stop. When you lift your foot from the brake, the engine restarts. In real bumper-to-bumper traffic, the engine could be stopped and restarted many, many, many times. (Anyone see a problem here?)
What I wind up doing in bumper-to-bumper traffic is selecting "low" gear and the stop-start system is disabled.
Ted @ May 23rd 2006 4:23PM
When you couple this with the other ideas they're planning (direct injection, steam power or something besides the engine powering the ac,etc) You have to give them a lot of credit. If they can make a sporty car save 15% of its wasted fuel usage, what's not to like?
JGH @ May 23rd 2006 4:26PM
I always wondered how the Accord hybrid would handle that situation. It's good that there is a workaround. I think Honda should perhaps use ultracaps and the electric motor to propel the vehicle in such situations. If you're in bumper to bumper traffic, it would be annoying to have the engine cycling on and off.
dave @ May 23rd 2006 4:45PM
Automatic Stop/Start? So, ummm, ASS? Nice one, BMW.
hitbyastick @ May 23rd 2006 4:45PM
Yeah and what happens to the oil pressure in that type of system? Seems the cylinder walls and piston rings would see 4 years of wear inside of 1 year with that kind of gimmick.
People, gimmicks are always going to be thrust upon you seemingly at random until somebody comes up with a real solution. This is not a real solution, nor are the hybrids. These two aren't even an efficient stopgap. Best thing to do would be to dust off the bicycle you got for Christmas eight years back and prepare to be sore for a while. Ain't no easy way out of this.
Phil @ May 23rd 2006 5:00PM
Ok this is going to give even more incentive for retards who rev their engine at every stoplight like sport bike riders do.
Zo @ May 23rd 2006 5:02PM
And if BMW is smart, they will have a switch to turn it off. Seriously though, if anyone has been on the I5 in the UK or around London, or L.A. or San Fran or the NY Metro area during morning or evening rush hour when its a parking lot for several hours, this feature is better than burning all the fuel and creating all the smog while just sitting there. Sitting at the stop light will not do you much, but anyplace where you just plain wait (e.g. airport, after a ball game, after a concert, during xmas shopping etc) it would be great!. I believe the current 06 3s have an electric motor for the fan, the A/C and some other items that is seperate from the motor and is not connected to the motor -- I can see them extending that concept to the start/stop motor.
I would love to know how this would work with a manual gear shift or on a steep hill unless they plan on using the Rover hill climb/decent tech it could be interesting. Also will be fun in New England snow storms when momentum is your friend.