how does that come into an mpg conversation.

good one.

americans are doing 55 on the freeway when they are calculating their mpg.

europeans are doing more like 70 when calculatin their mpg.

its fact that the faster you are going, the more drag you get, the more fuel you use, the less economy, etc etc blah blah.

Matt

its fact that the faster you are going, the more drag you get, the more fuel you use, the less economy, etc etc blah blah.

Matt

No its not a simple as that.

Sure if you are going at 90 or something silly you will burn of fuel at a quicker rate, thats simple becuase of the higher revs you constantly have your engine at (depending on you car / gearing ratios.).

Your car will be most efficent at a constant 60-70 MPH.  Its how hard your engine is working and how long it is staying at a constant speed, rather than stop start 30 mph town driving is the most inefficent way of your engine using fuel.

Air resistance has only part to do with it, the engine has to work harder to get up to that speed regardless of resistance forces in the first place.

I love it on the news where all parties involved from porduction to sale of petrol are acting like school kids going

"was not me, I didnt do it"

I love it on the news where all parties involved from porduction to sale of petrol are acting like school kids going

"was not me, I didnt do it"

yeah its like they are making out the cars all broke down by coincidence

Quote from: Serious

56mph is supposed to be the most economic speed, which is why the US ended up with 55mph speed limit.

sounds criminally slow to me, id never get anywhere at that sort of speed

its not that bad, if i am doing long distances on the DC/Mway i just get to 60 and wack the cruise control on.

i get near 65mpg doing that, goes down to 50~ at 70

the engine has to work harder to get up to that speed regardless of resistance forces in the first place.

why? if there are NO resistance forces, then the engine wont have to work to get to that speed. if we could eliminate all resistance forces, wed not need energy to create motion.

say what you mean cos that doesnt make any sense.

why? if there are NO resistance forces, then the engine wont have to work to get to that speed. if we could eliminate all resistance forces, wed not need energy to create motion.

say what you mean cos that doesnt make any sense.

He means air resistance.