• Californians drive on the right side of the road!

• By law, everyone must wear a seatbelt and motorcyclists must wear a helmet.

• Speed limits are posted in miles-per-hour (mph). Generally, the speed limit on multi-lane freeways is 65mph. On two-lane highways it is usually 55mph. The speed limit on city streets is usually 35mph. In residential areas, near schools and in areas with heavy foot traffic, the speed limit is almost always 25mph.

• Along freeways with heavy traffic, car pool lanes (or "diamond lanes") are identified by small black-and-white signs and by diamonds painted on the roadway. To drive in a car pool lane, you must usually have two people (including the driver) in the car. Some car pool lanes in the San Francisco Bay Area require three people (including the driver).

• Roundabouts are uncommon in California. Most intersections are either signed by traffic lights or by stop signs. Unless signed otherwise, it is legal to make a right turn on a red light (known as a "California stop") after you come to a complete stop.

• When on a motorway in Ireland, it is illegal to overtake on the left. However in California, though it is recommended that you overtake on the left, it is not against the law to do so on the right.  

• Petrol is a lot cheaper than in Ireland (Don't forget Californians call it gas !) and is readily available. However, if you're on a long drive in a wilderness, desert or lesser populated area, please remember that the petrol stations are less available than in the cities, so it is best to ensure you have enough fuel to last the entire journey.

• The California Department of Motor Vehicles (DMV) publishes a downloadable version of its California Driver Handbook (2.39MB) which thoroughly explains California road rules. You will require Abode Acobat Reader to be installed to read this document.

• Travelling with children: Every car rental agency in California is required by law to provide for rental to adults travelling with children under six years of age, child passenger restraint systems that are certified by the manufacturer to meet applicable federal motor vehicle safety standards for use by children weighing 60 pounds or less, are in good and safe condition, with no missing original parts, and are not older than five years.