dune buggy

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A recreational vehicle having oversize tires designed for use on sand dunes or beaches, especially a light vehicle with a modified engine mounted on an open chassis.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A recreational vehicle with large tyres / tires, designed for use on beaches and sand dunes

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a recreational vehicle with large tires used on beaches or sand dunes