srw
It's a bit more complicated than that...
actually.....to introduce a complicating factor....there are times when I can see an opportunity for a driver to pass, and I'll wave him or her past in a big way, while slackening off the pace a bit.
I'd never actually wave someone past - the decision whether or not to overtake is always the driver's. But I'll quite happily pull in, turn round and look meaningful. Whether I'm in a car going slowly or on a bike.