Heathrow has started charging £5 for using the drop off zone and the short stay has a minimum charge of £7.50. Given that the traveller is fit and active, and both have mobile telephones (mounted in car for the driver and so legal to use while travelling), what is the best place for a passenger to be dropped off or picked up by a car?
My definition of "best" would probably be whatever is easiest for the driver, even if less convenient for the passenger. I have noticed there are some laybys in the traffic system that are marked "No Parking" rather than "No Stopping" but the ones I saw are on the other side of a very busy multilane road. My instinct is that crossing the road would be unsafe and so other options would probably be better if there is not a safe pedestrian route to the terminal from there.
[EDIT]From the answers, it appears a popular option is public transport. One of the biggest considerations with that route would be a drop off/collection point outside the ULEZ. A small local bus fare would not invalidate such an answer.