fuel consumption carrying weight

No. It depends very much on how and where you drive. For most vehicles the rolling resistance does not increase significantly with increased load, provided the tyre pressures are correct for the load, so that the effect of increased mass is to require more energy to accelerate it. How much more energy is required depends on the rate of acceleration you ask for. In the case of a low powered vehicle that you habitually drive at full throttle anyway, there will be little difference in fuel usage. Only in very hilly country will the energy required to climb hills be significant compared to the energy used to accelerate. JD

One would assume you are coming down again so very little fuel is used then compared to going up. I'd say it pretty much balances out which leaves just the added energy to accelerate the bigger mass.

Or to be precise a transporter load of them going down the A45, gave me an interesting view of underneath, I suppose that is somewhere to put the spare wheel, but I did not really think much of the design.

Doesn't work like that - the extra energy you use to increase altitude is used mainly to heat up your brakes on the way down. Certainly you use less energy going down, but this does not make up for all or even most of the extra used in climbing. But you are right, and it has to be very hilly for the effect to outweigh the acceleration effect. And even then the whole situation may have changed by, for example, a very winding road that reduces your speed considerably, thus saving more fuel than the extra used because of the hills (aerodynamic drag is proportional to the square of the speed, and is the major component of drag at speeds over about 60kph) JD JD

I've seen figures which seem to show a pretty decent straight line for fuel/distance plotted against vehicle weight. It's thrown off by changes in engine design over the years -- look at how different engine affect fuel consumption in the history of the basic Land Rover -- and short runs can be untypical enough to make the idea misleading, but as long as your driving style doesn't change it'd be a starting point.

Remember, gallons per mile, not miles per gallon.

Come down on your brakes round here and you get brake fade about half way down... Engine braking is a must. Yes, there will be more energy going into the brakes but only that from the height loss as you brake for corners, assuming you are not letting it run away on the straighter bits. B-) This is a hill that drops around 1500' in about

I certainly didn't notice any difference in fuel consumption when we moved up here from the relatively flat south.

which would seem to be negligable then, jolly good.

Regards. Mark.(AKA, Mr.Nice.)

I saw one in some service station somewhere on thursday, had a crowd of folks in suits surrounding it.

Regards. Mark.(AKA, Mr.Nice.)

One was just parked outside work. It's a transit with a glass roof.

Paul

Megalowmania vaguely muttered something like ...

I'm actually getting to like the looks of it ...

I'm not.

Regards. Mark.(AKA, Mr.Nice.)