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I note with some interest, that several popular leading european automobile manufacturers, such as Mercedes, VW, Nissan, Hyundai, Kia etc are making a big deal of their start/stop engine technologies and that the application of this, to something like a Honda 1.2 litre Jazz 'just' manages to move its annual VED down from around £120 to £30. By deploying this to just one 'mid price range' model with the smaller 1.2 litre VTEC engine, Honda have managed to sucessfully get an official European Test Cycle result of 120 gm per km - the 'magic' threshold, which all modern supermini and makers of quite large turbo-diesel limousines strive to achieve, in what is are very competitive but contrasting segments of the european car market.
My questions are as follows:
(A) Does the additional initial cost of adding this technology really pay for itself over the long haul ? {cf (C) below for a list of some of the items that add cost to manufacture}
(B) In real world '4 seasons' mixed urban and extra urban UK driving, does it actually really save much petrol?
(C) Are the more robust starter ring, starter motor, larger capacity battery systems and associated monitoring systems as reliable and trouble free as the conventional arrangement, where you can always simply choose to 'turn off your engine' for as long as necessary if 'stuck' in a motorway traffic jam etc.
(D) Are the benefits it apparently confers, such as a reduction in urban roadside exhaust fumes and consequent eco-environmental benefits to a lrge extent 'cancelled out' by the neccessity to replace car batteries, starter motors etc more frequently than would otherwise be the case?
(E) Is s/s technology little more than a cynical way of 'fine tuning' the European Driving Cycle test results to squeeze into one VED grade lower and thus claim technological superiority over a rival manufacturer?
I have been attempting to make my own comparative measurements on a Sept 2001 (61) registered 22,500 miles (and rising) 1.25 litre supermini over intervals in excess of 1200 miles and it is proving difficult to see any significant benefit or improvement in fuel economy by manually 'emulating' the behaviour of a well engineered s/s system such as might be found on cars with sophisticated alternator and battery management systems designed to optimise fuel economy and overall performance i.e. as per BMW 'efficient dynamics' specifications. P.S. I keep my car (AGM) car battery well 'charged up' at all times both summer and winter, by the use of an intelligent external charger purchased from a well known 'german owned' supermarket chain for just £14. Without knowingly or deliberately modifiying my driving style, routes taken or overtaking/braking habits, the uncertainty in mpg measurement appears to be of the same order as the 'benefit' I am trying to measure and is in reality not really any better than what any sensible driver would do, namely to 'switch off the engine' when stationery in any prolonged 'traffic jam' situation.
Once you are averaging between 11 and 12 miles per litre 'brim to brim' - measured over three or four 'tank fulls' of petrol, then the relatively small benefits, shown after the addition of s/s technology, as refllected in typical Official European Driving Cycle Test results and A to B comparisons, become diminishingly small.
Do not even get me started about the dubious 'benefits' of 'paying through the nose' for a multi-cylinder car with 'active cyclinder management' etc - the best way to make any IC petrol engine more efficient is to put a reliable and properly engineered exhaust driven turbo charger on it. Period !
Comments or any anecdotal evidence regarding any of the above would be much appreciated. :-)
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