Based on HMRC Statistics approximately 1 million employees have a company car, its the 2nd most popular benefit in kind. The most popular benefit in kind is Private Medical Insurance (2.2m employees).
Often employees will change cars or start/stop having fuel for cars during a tax year and the tax on company cars can be significant, you can use this HMRC calculator to assess the the tax.
HMRC have just introduced a new Check and Update Service for Employees so that you can make sure HMRC have the correct information
You may find that it would be better for your employer to give you a loan, beneficial loans up to £10,000 aren’t a taxable benefit.
There companies like Maxxia that promote salary sacrifice schemes for cars