Possible stupid question - helmets

[sunbeam alpine]

Is a full-face bike helmet suitable for use in a car on a track day, or is there a difference?

Have been invited by b-i-l to take a space on an experience day with 3 different types of car (including a caterham-type thing).

As it's actually a day hosted by one of his suppliers, I guess that most people won't have their own helmets, but I'd prefer to wear my bike helmet than use a "loaner" which has been worn by loads of other people.

I'll look enough of an idiot with my driving, without adding to it!

[Trev450]

Bike helmets are fine for trackdays. It's MSA events that you require a car helmet for.

[tr7v8]

I wore a bike Helmet yesterday at Brands & it was fine. It was actually an Aldi £40 special & I have a weird shaped head & it fitted fine.