I'd agree with 5. We have the same.
I live 30 mins from LHR so 5 is a no brainer as a taxi costs way below the price of leaving the car at the car park.
I also agree it makes sense from an H&S point.
I take the car allowance and just need a 4 door tin top insure for business.
My German colleagues have the full blown pool / hire car thing.
