On comparison sites or on the phone, I always get asked if I'll be using my car to commute to one regular place of work. Now, I work offshore and generally go to a hotel in Aberdoom the night before flying. Could I drive my car to the hotel and still claim I'm SDP use only? I don't work at the hotel and I can't technically drive to the rig, so I can't see why I should pay SDP + commuting premiums, especially given insurance co's propensity for taking things literally when it benefits them.
All hypothetical, of course. It costs more in petrol and parking than in train & hotel fees.