Well, it looks like the record that was recently set in Montréal, Canada, didn't last very long. 431 electric vehicles in one spot was very impressive, but this year's World Advanced Vehicle Expedition (WAVE) has cranked things up a notch and gathered 507 electric vehicles in Stuttgart, Germany. The count has been made official by Guinness World Records.
They obviously had a lot of fun posing the EVs, as you can see in this video (which I believe was shot by a RC drone):
That's a nice reveal at the end!
Wave did something similar in 2013, but they only had 305 EVs:
These types of events are great at raising awareness and creating a community of EV owners. Someday plug-ins will be so mainstream that these types of events might not make as much sense, but in the meantime, they're a great morale-building exercise for the very important early-adopter crowd. Without these people at the avant-garde, few things would ever change...