it completely depends on whether the cost of the car she chooses is greater or less than contribution from the company.
for example my car is part paid by the company (including tax, mot, insurance repairs etc) however i contribute a nominal fee per month which then makes it my car leased from the company thus avoiding having to declare it as a 'benefit' to mr tax man.
If the car was completely paid for by the company again it would only have to be declared to the tax man if you are using it for private millage.
Hope this helps a little if you have more questions etc get in touch! The Gov. website explains in more depth.