If you change your mind after your car has been ordered but before it has been delivered, the vehicle dealership and/or the leasing partner will charge your employer all direct costs including third party supplier cancellation charges incurred by them as a consequence of such cancellation which could potentially be as much as 10% of the P11D (or payroll) value of the car (depending on the terms of the deal, the specific vehicle ordered and the stock availability).
Your employer will collect this charge from your salary (and this may be taken off several months’ salary, depending on the amount due). If you are no longer in employment, you are still responsible for making payment for such charges. Your employer may contact you to discuss and agree an appropriate approach to collecting payment in such circumstances.
If the delivery of the car is delayed then you are still contractually committed to the scheme.