Small engined cars might be fine putting through Sydney for a commute, but are not much good if you actually need to carry something (of weight) or in hilly areas outside cities. In mountainous areas the lack of torque (based on cylinder size) can result in heavy fuel usage as the poor little car is too underpowered to cope with the climbs.

Towing a caravan with a 2.5L diesel might be fine if you are heading across the Nullabor or Hay Plains, but for your average Victorian heading to the Gold Coast it would be a disaster. Again the issue of it being underpowered would result in heavy fuel usage. My dad drives a very efficient 2L diesel sedan (thats 22 years old). Its got 600,000 kms on it, has only JUST had the motor rebuilt and gets 1000km to a 60L tank. BUT he lives on the Hay Plains, so no city traffic or hills to struggle with.

No Admiral the market will NOT decide when peak oil occurs.
It will be decided by geology !

Country Gal;
Yes I think the points you make are correct.
I am not an expert, but just common sense would indicate that.
However to be definative about it you would have to find the ratio of
flat running to hilly running and another input would be the steepness
of the hills. Also a further complication would be the effect of running
down the hills. A very complex calculation.
The only alternative would be to measure it for two specicic cars and
a particular district.

The price and availability of fuel will drive what you do anyway.
It might be advisable to lay in a stock of older cars as larger cars
just might not be available.
Once rationing starts you might be looking for a good horse.

Admiral V.S.-- "The market will determine when 'Peak oil' arrives."
No it won't. Peak oil, for free flowing oil, will be determined by the cumulative geological natures of the reservoirs already being exploited unless we find some gigantic new reservoirs which is unlikely.
"...busybodies stay out of my life..."
Anyone wasting resources is adversely affecting the future of my grandchildren and yours. I am aiming to protect and benefit that future. Who should stay out of whose life?
Leigh-- You commented that "the problem will be solved by free enterprise movers and shakers." I doubt that. I attempted to point out some of the debacles caused by some of those characters, even when operating within large corporations. Some of us are trying to prevent our civilisation from going over a cliff. It doesn't much matter to me personally. I've had more than my three score and ten
Foyle

There are always some around who want everyone else to conform to their vision. Well a society full of these types is not worth having, so foyle, bon-voyage, & please, take your mates with you.

Anyone who thinks these horrible cities you live in, can survive the loss of the car, & road transport, is a twit. With out the truck to collect your food from scattered, & far-flung production areas, & transport it to, & around your cities, you are stuffed. Rail can't supply cities developed with, & for road transport.
You are going to have to live within horse & cart range of your food sources, if road transport fails. Better start looking for a new fuel.

I'll put the stallion in with a few mares, next year, if you like. It would be interesting to see how you would handle the manuer in a horse drawn city of 2.5 milloin.
Good luck.

"Some of us are trying to prevent our civilisation from going over a cliff." (Foyle, Friday, 29 June 2007 7:20:19 PM).
I guess I have more faith in human ingenuity.

Hasbeen said, "Better start looking for a new fuel."

I think you should have said "Better start looking for a new foal."