Besides this dealer, the obvious place to seek information and advice about golf carts is the local golf courses. They will know all about local laws on use, and probably know about mods to increase speed or performance, and be able to advise on the best cart for your friend's intended use/purposes. I'd be looking to talk with the service manager, not some kid wrench turner.
Valuation, (maybe) repairs, parts too.
They may have an opinion that the brand of cart your friend is looking at is a poor choice. They may have carts for sale. And like any other business, they may be advising in their own self interest.
If it was me, I'd be trying to get something that didn't require me to get tags, registration, and insurance (government regulation), but that may not be possible for intended street use.
All manner of goofy gas and electric carts, minibikes, skateboards and scooters go blasting around my neighborhood (10-30 over the limit) with no plates (and probably no drivers license by most). My 40 something backyard neighbor has one of those battery single wheel skateboards he rides to work 10-15 miles away. He's all armored up with full face helmet like an imperial storm-trooper, and does mostly walks and trails, but has to run a few streets (illegally I think).
Another neighbor friend has a nice new lithium powered scooter he says will do 60-70, and one of these days I'm going to see if I can ride it around without killing myself.
