I've been friends with "Susan" for about 8 years now. She's part of my inner circle of best friends and the four of us meet up at my house every couple of weekends to play games and hang out. We all met in grade school and we're now in our early 20's.
Because of the location of my house usually "Arnold" will pick up "Gerard" and Susan and bring them over in his car. I have the best house to hang out in and all the board games and D&D supplies and such are stashed here.
I've been having the group of them over for years and Susan is always late. We joke about it, it's a known factor in our friend group and we put up with it, but it's really starting to wear thin.
The problem is that she'll claim she'll be on time and stick to that even when she knows she's lying. I'm talking down to the last minute. Arnold and Gerard will confirm that they're going to pick her up at 1:30 and at 1:20 text to confirm where she is and she'll say she'll be ready. Then they have to wait 30 minutes for her to show up at the arranged spot because she was still a 25 minute walk away from the meetup when she said she'd be on time.
Susan knows how long it takes to get places (at least within 5mins, I'm not expecting NASA levels of accuracy here), so the frustration comes from the fact that she won't just admit that she's late so we can plan around it.
I am very good friends with her and the rest of the group and I'm fairly sure I can be toneally appropriate about broaching the subject for us, but I have no idea what words to use.
What do I say to Susan to make it clear that we're not mad about the fact that she's late, but that it would be a lot easier if she'd just come clean about it?
To be clear I'm not trying to change her late behavior. She's always been late and she'll probably always be late. We're used to it. The problem is the strain it puts on the rest of us waiting around for her to get somewhere / be ready / do something. We could use the time for other things and only show up when she's ready to go.
UPDATE
Thanks for all the feedback guys! However,
I am not looking for more suggestions to tell Susan a different meetup time.
Please stop suggesting it! I respect her too much to lie to her; it's rude and underhanded.
Additionally, as I stated in my question I am not interested in fixing the late behavior. The only thing I want is a way to mitigate her incorrect estimations of time.