If you plan to rent a car in Europe, it would be wise to familiarize yourself with the operation of the manual transmission. The vast majority of rental cars have manual transmissions. There are only a limited number of automatics available.
The very concept of 'car' is radically different between North America and Europe. Whereas in the US and Canada size really matters, Europeans look for fuel economy and have cramped parking conditions in mind. Here are some hints on choosing the right car when renting.

The very first thing to bear in mind is the transmission. Whereas most rental cars in North America will be equipped with automatic transmission, manual transmission is the norm in Europe. In addition the gearshift will be to the left of the driver. If you are not familiar with a manual transmission be sure to select an automatic. And remember that the 'exotic' automatic transmissions may sell out fast, so book early.

Most rental cars are standard European or Japanese vehicles, built for cramped road conditions and comparatively short journeys. Especially the lower categories (Sub-Compact and Compact) are typical 'city cars' for the occasional user. Even 'mid-size' in Europe would be rated Compact in the US. So expect tighter conditions and choose a larger vehicle if traveling long distances.

Cars are smaller and Europeans are used to them, so this leads to different car ratings. In the US, a car rated for two adults and two children, would be rated for five adults in Ireland. If you are in any way larger than the average European (5 ft 7 in, 165 pounds) go for a larger vehicle.

Luggage space in European and Japanese cars can be tight. Sub-Compact and Compact vehicles will more than likely be of the hatchback type with no actual trunk and a somewhat cramped storage area in the back. Getting four adults and their luggage into a Sub-Compact is nearly impossible. If you are planning to take your full baggage allowance go for a Mid-Size at least. Do not plan on leaving your luggage in view while touring, this will attract undesirable attention.

When looking up European rental cars you might notice that air conditioning or cruise control are not necessarily included in the specifications. You will not really miss them. While air conditioning can occasionally be nice during the short Irish summer, cruise control would be of no practical use at all.