The other white e89 that I've seen a few times followed me almost all the way to work the other morning.
I was feeling self conscious cos my car was minging and his looked spotless. Had the roof down, so when I turned off at the mini roundabout I waved to him (by sticking my hand up in the air) to acknowledge that I'd seen him.
Gotta feel jealous of all the other lucky people on the road that morning being able to see two e89's in a row
Finally... 12 months of commuting up n down the M3, M25 and dozens of passes of various Zs with no "contact" and I get a "stealth" wave so I obliged with my own version in return, not sure if you are on here (GN16 Blue Z roof up ) but white Z4 (Roof down ) passed me up the hill towards Bracknel turn off heading towards M3 > M25 intersection.
The 'Martini' E89 - subject of a photo thread on here if I remember right. Top folded and the stripes broke the shape - could only tell what it was from the back!