BIK when director is outside UK for part of the year

I have a director that is UK resident for tax purposes, and stays in Finland every weekend. He also spends a lot of time out of the country on business.

He has the benefit of a company car from his UK company, on which he declares a full BIK.

My question is, as he only spends a proportion of his time here, is he liable for the full BIK, or can it be restricted? I appreciate it is "available for private use" all year round, but he is quite obviously not using it if he is outside of the UK.