Most economical motorway speed?

Originally Posted by Moo

Headwind or Tailwind?

Laden or Unladen?

[embee]

A few misconceptions being quoted I'm afraid.

62mph (or 56mph) is not the most economical for a car. Folks see numbers quoted in brochures etc and think that's the "best", but it's just a regulatory requirement on manufacturers for quoted figures to be at certain conditions, it's not the "best". You get "urban" and "extra-urban" (= open road), or maybe 56mph (=90kph) and 75mph (=120kph).

For most cars the best steady state economy is usually just under 2000rpm in top gear (for level ground etc). That's a combination of engine efficiency, road load requirement etc. You find that the thermal efficiency of a typical petrol car engine drops off quite dramatically at much below 1750rpm, so gains in friction etc are offset by losses in thermal efficiency. Diesels are a bit different.

Don't confuse efficiency and economy.

Efficiency is getting the most mechanical energy out of the fuel, economy is using the least fuel. You can be very efficient but still use a lot of fuel if you're demanding a lot of energy.

Petrol engines are most efficient at around max torque speed and something like 3/4 throttle (or more precisely 3/4 load). However that will equate to something like 100mph in top on an SV, and economy will not be good.

I can't put an exact value on where is the best economy, but the others have more or less summed it up. Avoid wide throttle openings, don't rev it hard, use as high a gear as it's happy with, try to maintain constant speed, and somewhere round 50mph in top will get you a long way.

(edit - having said that, your question was for motorway, so bear in mind safety too, follow something at a safe distance in the left lane).

Originally Posted by wyrdness

Laden or Unladen?

African or European?

Originally Posted by Grinch

I found the best way to keep the bike economical is not looking at the speed but at your revs, try to keep them below 6k (7k can be ok), but above 4k. As then the engine is struggling to much as wastin fuel. I found doing this could at between 20-30 miles to a tank, another trick was to lay down as this would add between 10-20 miles on a tank. And I know this well as I did 130 miles a day on my cury S.
Remeber gunning it at the lights and bag gear selection will waste fuel, keep looking ahead and plan your stops, starts and gear changes. Then you to will get 60mpg plus.

LAY DOWN....surely you mean tuck in! steady 6omph n nice n smooth throttle action when overtaking will give you good fuel return. few blats of the old throttle n you start gulping it down.

[quote="wyrdness"] Since bikes are more aerodynamic than cars,/quote]

now that everybody else has beat you up, I'm going to take my turn

bikes have a smaller "frontal area" than a cage, BUT aerodynamics/ coeefiecient of friction is waaaaay worse, especially naked bikes.

that said, I have found the way to get the best fuel economy, bike or car

is to drive/ride like you have no brakes, slow steady accelerations to get to speed, coast up to stops.

Originally Posted by SVeeedy Gonzales

Or get one of those 1-2 litre motorbike petrol cans that go under the seat/in your backpack if you're really worried.

Interesting, got any links for these? I wouldnt mind one as I get phenominally variable fuel consuption and have been nearly caught short on more than one occasion.

[Biker Biggles]

Dr Rich----Do you really have to lower the tone of this thread?We don't want to know about about your personal habits or how often you get caught short.
Yours,disgusted of Tonbridge Wells.

Voila

http://www.getgeared.co.uk/acatalog/...etrol_Can.html

Originally Posted by SVeeedy Gonzales

Voila

http://www.getgeared.co.uk/acatalog/...etrol_Can.html

Excellent, thank you. I can fit a couple of those atop my panniers.

I find the best economy at below 70mph, The drag increases above this speed.