In all cases, for hiring a car you will need a valid credit card, preferably with Chip-PIN recognition for the local deposit, identification (usually a passport or visa copy) and a driving licence (photocard-types are much preferred). Proof of Address (Utility Bills less than 3 months old are widely accepted). You may have to provide a pre-authentication of the credit card, so in case of any traffic fines after you return the car would be charged to your credit card. Check with your hire company before booking to ensure there are no complications on collection/delivery.

Unless specifically requested, rented cars will usually have a manual transmission (stick shift, or gear lever). They will run on unleaded petrol or diesel. You MUST NOT fill up a diesel car with unleaded or vice-versa - doing this is will cause major engine malfunctions and the engine will probably not start at all. Usually city diesel will be more expensive than unleaded at the pumps, but a diesel car is generally more fuel efficient.

Most car rental companies have airport bases. You can pre-book your car rental online and pick the car from the airport. If you are arriving into a major airport such as London Heathrow or Manchester and staying in those cities, public transport services are excellent and will get you into the city centres much quicker than a car would. It is much better to arrange the company to drop-off and pick-up at your hotel, although this may attract a fee of around £20. 

Road signs and markings are generally in English and use Imperial units (such as miles and yards) to show distances. Welsh roads have dual language signing (Welsh and English), though some remote roads are Welsh only. Many Highland roads in Scotland are signed in Scottish Gaelic as well as English, though again, remote roads can be Gaelic only.

Conversion from miles to kilometres and yards to metres: 1 mile = 1.6 km, 1 yard = 0.93m

 All the international car rental companies are present, as well as the odd local firm, these include: