The Arrows shown here
http://en.wikipedia.org/wiki/File:Arrows_A2_1.jpg is the one from Nuerburgring.
Try google for pictures of Arrows A2 and you will find that the Mass Arrows with the modified hoop still exists and is on display somewhere, same for the Patrese car. Both have no engine cover and are in much more accurate Warsteiner livery.
So if the japanese car hasn´t found his way back to Europe there may be a fourth car
(I´m just kidding)