Now the problem with that is, You're adding a lot of weight, What I actually do is fill up £10 at a time, fill up again (usually in 2 days time) rinse and repeat, less added weight, moar MPGz.
i've taken a lot of steps to reduce my weekly fuel cost of £50 down to £30 over a near 50mile commute, i haven't hit vtec yo in over 2 months (this actually makes me sad) £10 fill ups each time, car doesn't see over 3k rpm, annoy a lot of people on the M4/Dually's by sticking to 55MPH.
No.