Stick to the golf cart.
There's nowhere really to go anyway.
Renting cars in Honduras is fraught with unexpected and unseen problems. Certainly, the laid back world of Utila is a bit different, but in Roatan (and mainland Honduras), understand that life isn't as you might understand it back home. Here's what I've learned about driving while on Roatan, a few miles away.
1) The roads really suck. They are not reflectorized, striped or marked. Driving during the common rains is absolutely treacherous. Night driving is frightening.
2) Pedestrians and certainly farm animals seem to have no concept of why it might be advisable to stay off the road surface. Bicyclists with passengers disappear into the darkness. Unlit vehicles are the norm.
3) Drivers are unfamiliar with the physics laws relating to two objects occupying the same space at the same time. They drive by braille.
4) Vehicles are barely safe for the roads. Headlights and brakes are luxury items, brake lights are NOT a given.
5) Frequent annoying stops by Tarnsito Police for "inspections" and paperwork registration apply to rental vehicles as well.
6) There are no trauma units, much less a hospital which is prepared to service an accident victim. Ambulances are basically pick up trucks.
7) You, the driver, are absolutely responsible for any incident you are involved in- most notably if you are a foreigner. If someone jumps onto the back of your vehicle and you ask them to get off, you might have to support them for life even if the injure themselves while climbing off.... much less if they are injured while you are driving.
Again, in Utila, there is precious little need for a real car as a tourist. If you want to go for the short ride around this tiny island, hire a driver. I would suggest the same while on Roatan as well.