Im switching from a 225 to a 318, is there a big difference in fuel cost?

You will like the 318, in stock form it's almost 50% more HP then the slant with no real penalty in MPG. You should be able to add 100 HP to a stock 318 with simple bolt ons and if you run highway gears your MPG will be pretty much the same. My Dart is set up similar to Rumble's except I am running 2.76 gear, 600 holey on an old streetmaster intake, cam is stock 340 grind [email protected] intake, [email protected] exhaust lift I think is .429 &.444. Has a good tune on the carb and advance curve, runs 89 octane. Standard low comp short block duals with manifolds, factory high stall convertor and transgo TF-2 shift kit. Car has ran 15.4 and will get 20 MPG highway easy if you keep the speed down. It has done a best of 23 MPG on a warm day driving 55-60. I had an 78 aspen with the super 6 set up with bigger exhaust and a few other tweaks and it was hard pressed to get 20 on the highway and was over 2 seconds slower in 1/4.