Read this one a while back. Boss and secretary are traveling in a car on a work related thing. They have sex along the way. Setting was somewhere in the UK I believe. I'm not 100% sure but the boss may been have been married as well so he was cheating on his wife as well.
I appreciate any help, hope someone knows what I'm talking about. I think the author had a few other stories based in the UK as well.
Thank you!