On Sun, 13 Apr 2008 23:13:02 +0800, "TE Chea" <4ws@gmail.com> wrote:

>Such a graph must be stupid, of course consumption rises
>with rpm
>
>| gas mileage usually decreases rapidly at speeds above 60 mph.
>Not necessarily fr 60 mph, big factors incl
>[i] exhaust*manifold : cheapo 4-1 short branch * can give
> ¾ of maximum torque @ low rpm <1000, but gives <½
> of maximum torque @>3000 rpm, & even less @ higher
> rpm
>[ii] voltage & ampere from small single coil ( esp if hot )
> drop fast @>3000 rpm : sparks will be too small to
> ignite enough fuel before pistons reach b-d-c, esp where
> only cheapo carbon core cables are used
>[iii] cheapo mineral oil's coarseness are apparent only @ high
> rpm when only the most slippery oil ( e.g. synthetic with
> fullerene ) can produce high torque.
>[iv] gear ratios & axle (tyre) height

Needless to say, this guy is wacko. By far the biggest factor in poor
fuel economy at high speeds is wind resistance. Many vehicles (e.g.
big SUVs) run less than 3000 rpm at speeds above 60 mph and get much
reduced fuel economy due to their barn door aerodynamics.

Of the above, only iv. will have any noticeable effect on fuel
economy. To the extent that i. reduces power at high speeds it may
actually reduce fuel consumption.