You don't have to shut off the engine to avoid stopping at a red light, you just have to lift your foot from the gas pedal and the engine drop to 0 fuel consumption then you just coast to the light the same way if the engine would be shut off, except you retain all controls. Much safer and does not cost more fuel. I coast to red lights all the time that way.
Because of that, it's not worth shutting off the engine before the car is fully stop because one might not even need to do so because the light will turn green. There is really no advantage of doing this. I don't even see an advantage in shutting off the engine if the light is not long enough.
If you have modified your car to have a system for engine stop and start then it's probably safe, but most Micro owners will not have this system and would probably be at risk by doing what you do.
Originally Posted by
Daox
Its not illegal in the least. Its also really not dangerous if you know what you're doing and know how to drive that way. The same could be said of driving in general. Driving in general is dangerous unless you actually know how to drive. Same with flying a plane, using heavy machinery, etc. This really isn't any different, its just uncommon.
As stated, engine wear is increased. However, it is minimal since its not a cold start with all the oil in the sump. I've personally never had an engine or starter issue in the 10 or so years I've used the technique. Thus I consider it a non-issue.
The fuel saved turning the engine off on the way to the light is not as much from not having the engine running as much as maintaining momentum. The key really is to not have to stop for the light at all. If I'm going 35 km/h when the light turns green vs 0 km/h that is that much less fuel I need to burn to accelerate back up to speed. In certain cases I may employ engine braking to do this. That is a viable technique though often not the most efficient.
Again, knowing how to drive this way is key. I'm not disabling any car features. The engine is killed, but the car is not turned off because I do it via a momentary switch that kills power to the injectors or ignition system. ABS, electric power steering, airbags, cooling fans and everything else electric is unaffected. Hybrids these days do this all automatically, and more and more non-hybrids are starting to use start/stop systems to save fuel. My techniques are no different other than there isn't a computer controlling them.
I personally don't do this so much to penny pinch. I own fuel efficient cars that are efficient to start with, however this does increase fuel economy even farther. Mainly, I find it quite fun to drive this way, and I enjoy trying to beat my own high score. So, it becomes a sort of game. The additional fuel savings is a nice perk I admit. Driving normally is boring IMO. Driving aggressively can be fun, and I do enjoy this aspect of driving as well from time to time (usually on my motorcycle). But, it also can become frustrating quickly as traffic gets in the way.
I'm not sure why this riles people up so much except that they don't understand what is actually going on and assume the worst. If you don't like this way of driving don't do it lol. You're not gonna ruffle my feathers, and I'm not making anyone drive a certain way. I'm simply explaining how I do it and how you can save fuel. So, I hope that clears up some of the misconceptions and questions, but feel free to ask away if there are more.
__________________________________________
View my fuel log 2015 Micra SR automatic: 7.0 L/100 km ... 40.4 mpg (Imp) ... 14.3 km/L ... 33.6 mpg (US) ...