Probably becuase the Merc has more horsepower and is therefore less affected. That Zafira figure is certainly a shocker.
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TourVanMan TM < Ex RF >
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Maybe the Zafira has extra strong a/c to cope with its glass area? I have a Merc C Class and the a/c struggles in very hot weather, so perhaps the compressor isn't particularly energy sapping.
The surprise to me is how little the Panda is affected.
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If you look at the percentages, the Zafira doesn't come out too well.
But, I don't put percentages in the tank, I put litres in.
When you look at litres, it's the VW that takes the drubbing!
Number_Cruncher
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When you look at litres, it's the VW that takes the drubbing! Number_Cruncher
at 28 & 33 degrees yes, but at the more GB friendly 20deg, the only one that would cause me any real concern is the Zafira - especially if I was doing a shed load of 30 mph work !
MTC
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Mmmm - fair enough MTC, but I think that when you consider the smaller glass area, and smaller volume of air in the VW which must be cooled, I don't think the Zafira comes out of the comparison as badly.
I think that the test method might also be a little dubious. If, for example, via a quirk of the car's gearing, one car was revving harder than the other at a given road speed, there will be more energy wasted in the aircon - especially if it has a fixed displacement compressor.
Number_Cruncher
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My father-in-law has an Omega with instant fuel read out on the computer. I don't know how accurate it is for exact mpg but it seems to react well to changes. E.g. Maintaining speed (ie raising revs) from the flat to a hill on the motorway produces a change in a few seconds of a few mpg. Switching the dual-zone climate control on and off produces a change of less than 1 mpg. Not a scientific study but it hardly seems worth sweating for that saving.
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Switching the dual-zone climate control on and off produces a change of less than 1 mpg.
My C Class is the same - it's an average indication in that, but I can have balanced on cruise on the motorway such that a short hill drops it .1 or .2 and a down hill stretch puts it back up again. Switching the a/c on and off seems to make mno difference at all (except that the interior goes cold!).
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Just checked my brim-to-brim records for a Golf 2.0 TDI DSG used in Spain. September to May 5.78 l/100km (48.9 mpg) - Jun to August 5.86 l/100km (48.2 mpg) = 1.45% increase (decrease).
Would be interesting to see corresponding tests for driving with windows/sunroofs open v closed - steel wheels v alloy wheels - clean v dirty cars
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Anyone figured out what the requested internal temp was. If it was 20 degrees then the aircon should hardly be working with a 20 external temp or was this done at max cooling/min temp. Regards Peter
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Internal temperature was set at 20 degrees.
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