International standards on fuel consumption

Apart from hybrid and diesel models, Toyota Altis seems to lead the class in terms of fuel consumption - a whopping 18 km per litre of petrol.

Does anyone know if such claims, be it from Toyota or Nissan, factor in the switching on of the air con ?

And when a dealer is faced with the question that the car is not as economical as the ads suggest, they salesmen and mechanics will always give the excuse that the car is still new and the fuel economy will improve when the car is ‘seasoned’. When is the car considered seasoned ? 10,000 km ? Is there any truth that new car ‘eats’ fuel and fuel economy will improve over time ?

Fuel testing used to be done under rather unrealistic conditions, but I believe the new city + freeway mileage statements are fairly accurate. Of course, it depends a lot on your driving style and a certain amount of ‘specsmanship’ is always involved.

I don’t think it makes a lot of difference how new the car is. Sure, the moving parts need to ‘wear in’ a little, but that only takes a few hours of operation and I doubt that it really has a big impact anyway.

18km/l is hardly unrealistic - I think it’s just that Americans (and Taiwanese) are so used to cheap fuel and pisspoor engine design that they don’t realise what’s technically possible. I hired a 2L diesel VW a couple of years back that averaged a real-life ~20km/l over about 4000km of usage. I was impressed.

If you’re interested in the technical limits, have a look at this:

5300km/l gasoline equivalent, using a hydrogen fuel cell and (in my opinion) less-than-optimal power electronics.

I have the book (published by ETH) detailing the construction of this vehicle. It wouldn’t be practical to make or operate a road vehicle this way, but it’s still interesting.

I think it depends what testing standard (if any) the figure is derived for. The US EPA test includes some cycles with aircon (but no other optional electrical loads) applied.

I’m not sure about the EU test standard, but given that aircon is less widely available in European cars, and also given that the EU test routinely produces “better” figures, I’d guess not.

Re “early gas-guzzling syndrome”, Fuel economy and performance should improve as a car is run-in, because friction will be reduced and compression increased. This seems to be generally accepted.

The EU test specifies that the car must be run-in, but I dunno how they define that offhand.

I wouldn’t expect the effect to be huge, but IF its large enough to notice with most drivers “I put half a tank in on Tuesday” half-assed subjective fuel consumption monitoring, then it must be significant, though I’d guess it’ll vary a lot. Somewhere I’ve seen a figure of 5k (miles) as the point of significant performance improvement of a Ford SportKa but I dunno how soundly based it was.

Initial low compression would correlate with higher than expected initial oil consumption.

4WIW my 24 year old Skywing, which should be run-in by now, averages about 17km/litre (without aircon) the way I drive it. Not bad but I havn’t calibrated the odometer yet so the real figure is likely to be 10- 20% worse.