Yes, that's right. It's a Citroen Dyane. It's also traveling on Interstate 80 in central Pennsylvania of all places and I matched speeds with it at about 75 miles per hour. Furthermore, it was actually passing other vehicles on the highway.
All facts which seem very strange when put together.
You'll also notice on close inspection of this photograph that the car is leaning to the right. It would appear, judging by the "GB" sticker and plates that it was imported from the UK and the rather robust driver is sitting on the right hand side. All in all, a very odd find indeed.