In general yes, faster == more fuel burned, but it's not as simple as that, there are a lot of factors between the simple fuel burning and traction being put down to the road. The fact that I get better MPG out of my car at 50mph rather than 30mph suggests that. That's not to say that my car couldn't be made to be more efficient at 30mph than 50mph, but that's the way it's built, as are most.
But that's not true,if you could,but can't practically,drive at 30mph on the m/way you'd without doubt get more MPG than at 50mph.
It's the changes of speed and sitting in traffic jams that eat fuel,that's if,and it's a big if,the engine ever gets upto something resembling optimum temperature on urban roads,bearing in mind that most car journey are under 5miles.
The right pedal always uses more juice the further down it's pressed.
Add to that the stupid way people accelerate then brake eg;when running upto traffic jams,by their inability to read the road ahead and what Geriatix posted above about motorists and speed humps,it's clear that drivers actually believe
they're getting somewhere quicker
by what used to be termed as "clog and anchor" driving.These drivers wouldn't know smoootthhh if it caressed their face with silk scarf
The number of times I've been overtaken when cycling ,by cars as I approach a traffic jam which is clearly visible,is times out of number,only for me to then sail past them and said jam on the outside.
The problem is a psychological one actually the dim wits believe
they've gained something.
Like they believe they gain something by driving at 35 or 40 in a 30 limit,it's a fallacy they buy into.In the urban enviroment they only get to the next traffic light quicker and when everyone else is doing the same thing a jam is formed,which slows traffic even more and so it goes.