I’m thinking if you’re close enough to read this message you are following the vehicle way to close. I think the wise advice would be hard to view in good weather conditions. In a severe storm I’d guess it would be next to impossible to read. Not sure if the alert is serious, just a bit of fun or a bit of both. The license doesn’t seem to have a lighting system around it. So the words of wisdom wouldn’t be illuminated. In many States not having a lit license plate is grounds for a ticket.
Taking another look at the backend of the Tornado Intercept Vehicle in another picture – I see some serious headlamps. These could easily light up the license plate and the message around it.