I have to travel up to Leeds , I'm down south so it'll be mostly Motorway for miles on end! What's the best speed to stay steady at fuel econ wise - i.e, 60 or 70? Obviously I don't won't to take forever but don't want to drink the fuel.
It's a 94 WRX with decat. Any ideas please?

 

60mph .. or you might pull off 70 depends on your ratios lol as long as your off boost in the top gear it shouldnt drink too much

 

I went down to London at new years, 290 mile return and was pleasently surprised, even put 2 gallon of v-power in the boot just incase Had a couple of little plays on the motorway, max speed was in exess of the speed limit but so was the Porsche boxsters'
My advice would be, dont worry to much and enjoy, you too may be surprised

 

Just try to keep to as constant speed as poss with as little on/off the brakes/throttle as poss. It's this that 'kills' mpg IMO.