If you want to fit non-standard equipment into your lease car, you can, but read this guide so that it doesn't become costly at the end of your contract.
The short answer is yes, you can, but there are some important factors to consider before adding an extra to your car that could end up becoming costly for you at a later date.
The costs to fit, purchase and maintain those extras are solely at your expense. It’s recommended that all extras are supplied and fitted by an approved, qualified installer and that they conform to all legal requirements.
Any damage arising from the installation of extras has to be repaired at your own cost. At the end of your contract, if there are any visible holes in the bodywork or trim, they must be repaired to the standard required by the finance company. Any electrical alterations will also need to be restored to the original standard as well.
Ultimately, this shouldn’t discourage you from making changes to your car that you would do if the car belonged to you, but ensure that you are able to return the car to its original standard at the end of your contract, otherwise, there may end up being costly repairs involved.