Our car SatNav has a useful trick whereby you press the wee car shown on its screen - and it remembers the current location, saving it as a favourite - allowing you to be led back there later.
On exiting a cross channel ferry we used this trick - with the intention that we'd ask to be led back to the ferry later, principally so we could be led out of the morass of Paris, exiting the diabolical Periphique in the right direction.
This all worked well, but afterward, beetling homeward along the Péage, I noticed that the predicted arrival time at Calais was way too late to catch the ferry. This didn't particularly bother me as I knew the prediction was wrong.
A bit of faffing about with the SatNav's maps revealed why - it was smart enough to know that the ferry exit ramp we'd recorded is a one way lane - and that the only way to get back to that exact point is to take a ferry back to Dover, turn around and get straight back on another ferry to Calais.
Cleverness verging on the ridiculous.