Driving is on the right-hand side of the road. All the same rules as any part of the United States, except that the signs are in Spanish, the distance markers in kilometres and the gas sold in litres. The highway department places lomas (speed bumps) at strategic points to deter speeders. These speed bumps are even dubbed the "sleeping policemen". Distances are often posted in kilometres rather than miles, but speed limits are displayed in miles per hour. Speed limits signs are infrequently posted in residential areas, so it is prudent to stay under 30 mph unless otherwise posted.

Drinking and driving is never a good idea. Getting behind the wheel after just a few drinks can be deadly. In Puerto Rico, the legal blood alcohol level is 0.08. The penalties are severe for drinking and driving convictions.

The older coastal highways provide the most scenic routes but are often congested. Some of the roads, especially in the mountainous interior, are just too narrow for vehicles. If you do rent a car, proceed with caution along these poorly paved and maintained roads, which most often follow circuitous routes. Landslides are not uncommon as well.

During the first 120 days of arrival, a non-resident may operate motor vehicles in Puerto Rico. He or she must possess a valid, unexpired licence issued by any state of the US or by any foreign country that imposes requirements similar to Puerto Rico’s to grant a driver’s licence. Any time after 120 days, a Puerto Rican driver licence will be required to operate a motor vehicle.