How much is the pre-authorisation in the UK?

The amount of the pre-authorisation taken on pick-up of the rental vehicle is calculated as follows:
 
The vehicle rental price* + £300** MINUS any sum you have already paid when making a “Pay Now” booking. 
 
* The "vehicle rental price" includes the vehicle rental cost and all optional extras you’ve requested, calculated at the start of the rental based on the intended length of the rental. For the avoidance of any doubt, any “Pay at Location” amount you owe in relation to the vehicle rental (including any optional extras) will be included as part of the pre-authorisation and will be charged to you at the end of the rental (using the card provided for the purposes of the pre-authorisation, unless agreed otherwise).
 
** If you buy our “Fuel Up Front” product, we will reduce the £300 by the amount we charge you for the “Fuel Up Front” product
 
The £300 is included as part of the pre-authorisation in case we have to charge you at the end of the rental for any of the following: 
 
i.    costs to refuel the vehicle (where relevant); 
ii.    additional rental charges in circumstances where you fail to return the vehicle or any optional extras at the end of the agreed rental period [or to the agreed return location]; 
iii.    any additional charges or fines you incur relating to your use of the vehicle (which we have been notified of prior to you returning the vehicle, which will include, for example, charges relating to traffic violations); and/or 
iv.    costs incurred as a result of exceeding any relevant mileage restrictions. 

Where the pre-authorisation we take does not cover the charges you incur, we will request you make a further payment for the additional amounts owed.