I’m going away for a few days with someone who is in my bubble. They aren’t confident about using public transport atm so I offered to divert via London and pick them up. I wasn’t planning on splitting the petrol costs as I would be driving anyway but not through London. I had forgotten about the congestion charge which will add a total cost of £30 to travel costs. Should I ask them to pay it or would that seem mean & petty? They can afford it but so can I. Should I just suck it up and not mention it? It won’t occur to them as they don’t drive and probably aren’t even aware it exists.