RobertFT said:
Many thanks for all the very useful advice everyone. With regards the number of births I was thinking in terms of weight. My assumption is that more births = bigger van = heavier van = more costs to tow etc. Is this NOT the case?
Hello Robert,
Your basic general assumption about towing costs is I think correct, but there can be a few quirks which might belie that thought.
If we just look at the weight then yes the heavier the more it will cost to tow.
But size is a slightly different matter, caravans are by their nature quit large and boxy, so the aerodynamics start to play a significant part in towing fuel costs. As the aerodynamics air flows around a caravan are affected by tow vehicle just in front of it so it is perfectly possible for a smaller caravan to actually produce a higher wind resistance than a bigger van behind the same to vehicle it all depends on the individual designs.
I do recall that many years ago I had to drive a Ford Transit van with a Luton box body down to Fleetwood caravans in Suffolk. It was a very windy day. Fully loaded with 30cwt of goods and a following wind I averaged 50% more mpg compared to the return journey empty but with a head wind!
So that shows how much windage and aerodynamics does affect mpg.
In practice a difference in trailer weight of 10 to 15% wont make much difference to real life mpg figures, but the size might.