What is a good, 20-30ft fuel efficient motor boat?

[Liam]

My son is almost 16 and will be getting his boat license soon. What 20-30ft fuel efficient motor boat would you recommend? He will be taking the motor boat out with his mates during summer, so I don't want anything too fast or expensive to fill up. Second-hand boats certainly considered. Price limit of up to AUD,000-,000

[RichardC]

If you can afford $80-90K AUD I wouldn't think fuel efficiency would be an issue. I don't know of any 20-30 ft. "fuel efficient boats" that are not powered by a sail.

I would also question the wisdom of a 16 year old and friends operating a 20-30' boat.

As regular readers of answers will know, I seldom pick on askers, but It's hard or me to take this question seriously. Your knowledge of boats and boating seems at odds with your maturity, an alleged financial means.