For the first sample booking, the best deal was pounds 44.50 from Avis, on a fully inclusive basis. Europcar could offer AA members a rate of pounds 44.80 but non-members would have to cough up pounds 56. Through Holiday Autos you'd pay pounds 45 - if you could put up with the heavy background noise and distracted staff on the phone line - and with Alamo pounds 48. After that the rates rise at a very steep gradient. Budget would charge pounds 59, Hertz pounds 62 (plus pounds 6.50 for theft protection) and National Car Rental pounds 73.38 (although this rate be a more reasonable pounds 54.66 if you dropped the car off at the airport rather than in the centre of town). Apparently, Thrifty doesn't do one- way rentals.
For the second sample booking, hiring a mid-range saloon for a week in Edinburgh, your best offer would be from Budget, living up to its name with a rate of pounds 148.50. Alamo would charge pounds 160, Europcar pounds 167.99, Thrifty pounds 170, Sixt Sense pounds 174 and National Car Rental pounds 178.98. After that it's a hurtful pounds 196 with Hertz and pounds 215 with Holiday Autos. Most complicated of all - you have to answer a whole series of questions over the phone before they'll tell you the rate - is Avis. It charges pounds 200 for the week (or pounds 225 if you want to pick up your car in town rather than at the airport) plus pounds 1.12 per day in tax.
On the last lap of our Grand Prix of sample bookings, booking a Mercedes - or a set of similarly snazzy wheels - for 48 hours between Tuesday and Thursday, the best rates were quoted by Alamo (pounds 122.22) and National Car Rental (pounds 125.99). Sadly, neither would actually get you a Mercedes, since neither company has any - you'd have to make do with a Vauxhall Omega.
For a chance of driving away with the real thing (though none of the companies could guarantee a Mercedes), the best deals were Budget (pounds 144) and Avis (pounds 148). Sixt Sense quoted pounds 171, Europcar pounds 186 and Hertz pounds 228 (plus pounds 6.50 for theft protection). Holiday Autos couldn't say whether or not the company hired out Mercedes, and Thrifty couldn't offer anything even vaguely similar.
Before you pick up the phone and start your journey into the world of car hire, you should also bear in mind that the differences don't stop with the price. Before you can hire a car, each company has various regulations about what age you must be, how long you've had your licence and whether you hold a personal credit card. If it's price that drives you, be flexible about times, dates and pick-up points, and check whether there are any special promotions before you book.
To book call: Alamo (0181-759 6200); Avis (0870 606 0100); Budget (0541 565 656); Holiday Autos (0990 300 453); Europcar (0870 607 5000); Hertz (0870 844 8844); National Car Rental (0870 400 4502); Sixt Sense (0845 600 6660) or Thrifty (01494 751 600)