MacGregor 26X would be easy on gas
Go look at a Formula 280SS with twin 350's . . . or a SeaRay 280SS or 290SS if you can find one. . . . or a Chaparral 285
Those types of boats are a bit bigger than what you were thinking, yet have enough amenities without being a 'cruiser', plus you could do some amount of water sports with those boats.
The thing about cruisers that are in the 26 foot range is that they still have a single engine, yet are fairly heavy. Handling is nowhere as nibble as smaller boats or even bigger boats with twin engines, lots of v-hull 'waggle' at idle speeds, lots of throttle needed to get on plane, etc.
As far as fuel consumption, . . . typically fuel is the least amount of money overall spent on boats. So, there would be a lot more things to consider budget-wise with a bigger boat.