I was thinking about it being LHD and had made these assumptions :
the car in the photos is in Japan (Japanese writing on the road and one of the photos is on a web page of other cars in Japan).
it's not a one off, DIY sticker job. I say that, because a model maker has gone to the trouble of making a scale model of it for sale. This suggests it has some genuine (and presumably, interesting) history.
all SVXs came off the same factory line in Japan and so it was very easy for Subaru to access a LHD car rather than a RHD (i.e. they wouldn't have to import a LHD from a USA based factory)
if you accept that the signage is genuine and it really was in use at the Subaru Test & Development Center, then perhaps Subaru made a deliberate decision to use a LHD car because the majority of the cars were destined for the LHD USA market, so it seems sensible to carry out testing in a LHD model.
it's rare. Evidence of that is as simple as a
search (I've been doing a lot of that recently). The PPG pace car is far more common than this car. I assume that's because the PPG car appeared in front of many thousands of people at the televised race it participated in (possibly more than one race, I haven't researched it's history). Anyway, plenty of visibility promotes plenty of copies (there could be many PPG copies around) which just leads to that style having a much higher profile (more photos, more web hits) when compared to a car that never appeared to an audience or even in public as part of it's 'day job' (in use at the Test & Dev Center).
I hadn't considered the possibility that it was European destined.
I now have three sets of photos taken in different locations of what appears to be the same car. As best as I can tell, they are all LHD. Assuming all the photos were taken in Japan then that alone would be strong evidence that all three are the same vehicle (because LHD in Japan would be unusual, but not impossible)
But, on close examination there are subtle differences in the graphics.
eg, in the top photo there is a graphic just above the side indicator lens which is missing on the other two cars.