[QUOTE 5330062, member: 9609"]there is a speed where wind resistance becomes the greater user of fuel than rolling resistance, in a lorry that is mid 50s mph, and they reckon at this speed rolling resistance=40%, wind resistance=40% and other losses =20%
and in reality this works out really well - take a fully loaded bulker running at 44t, it is likely to be returning between 8 and 9 mpg on flattish roads. If it runs back empty (18t) it is very likely to return just over 13mpg.
44t is 145% heavier than 18t
40% of 145 is 58%
add 58% on to 8.5 mpg and you get 13.43 mpg
wind resistance has not changed and speeds will be similar.
these numbers work out very well for wagons.
obviously cars are considerably more aerodynamic so if anything rolling resistance will be more likely be a bigger factor than wind resistance, so if anything weight will play a bigger part.[/QUOTE]
Good answer - and extra points for hitting 00.00 as your posting time.