which would cost more?

A 4hr 10minute drive along 'A' roads (not dual carriageways) or a 3hr 25minute drive on mainly dual carriageways that is 20 miles longer in distance but obviously shorter in time? (Traffic wont be a problem as its a through the night drive).
Im trying to choose the cheapest way to travel fuel wise and would appreciate the help!

That's an interesting question - but I fear the answer lies in the the answer to another question, 'How do you drive?'

Most cars are at their peak fuel efficiency at about 50 -60 mph.

If you want to reduce fuel consumption - do not accelerate quickly - nor brake suddenly and keep your speed to within those limits

Are you the type of driver that always like to overtake the vehicle in front of you? If so your fuel consumption will rise.

There are a lot of issues involved when looking for maximum fuel efficiency - and not just the length of the journey.

I think it will also depend on how much stopping and starting you will do....roundabouts/speedlimits/junctions etc....I'm afraid I am an impatient person...it would always be the M roads and duel carriageways for me

If you go onto the AA route finder they will give you the fuel and mileage for both.
Elaine xx

I have no choice to be that slow driver lol- I have a rubbish car that is an automatic- but i do have patience to drive at 60ish on dual carriageways to save petrol .

thanks elaine- i'll have a look...