If you haven’t been given much information yet, you should opt for the cash allowance first when you start, then it’ll be easy to go onto the company car option after a few weeks once you have made your mind up.
A bit of advice if you have never had a company car:
IT IS YOUR RESPONSIBILITY TO TELL THE TAX OFFICE THAT YOU HAVE A COMPANY CAR – as soon as you get it. Same goes for fuel cards.
Don’t for one minute think you can get away with not telling them, becuase next time they receive your P11D it’ll be listed on there, and you do not want to end up paying back extra income tax the following year. Double income tax on a K code is proper pants.