There's a mystery regarding the IsoRivolta Vision Gran Turismo. It seems that there's another version of car, compared to the one that we have in-game. As you can see in the banner image here, there's a notable rear wing that's absent on the in-game version of the car. This version with the rear wing also appears in what's ostensibly in-game footage that's within the Zagato channel video. It also appears in all photos within the gallery below the embedded video. Furthermore, according to this link, the car is said to have a 6.2L V8 from Callaway, with a maximum power of 997 HP. However, the scale model that we see photographed in that link looks a lot more like the in-game version, as it lacks the rear wing. It is still puzzling, however, that in contrast to the aforementioned stats mentioned previously, the in-game model has a 4.5L Chevrolet V8 (specifically, 4494 cc) and a comparatively lower 559 HP, according to the GT Wikia's page for the car. It's also alluded, in both the video on the Zagato channel and in the car's flavor text, that this car is meant to race with both Ferraris and Lamborghinis. It seems very unlikely that the mentions of "prancing horses and raging bulls" could refer to anything else. But since the car is in Gr.X, this is more or less impossible given the limits we have for setting up custom races - I could see it being good for racing against the N-Series Huracan and 458, with some potential BoP changes between the three. Could it be that the winged version, with just under 1000 HP, was intended to be in one of the racing groups, where it could compete with Ferraris and Lamborghinis? Granted, it'd need quite the drop in power via BoP to be in Gr.3, and I can't think of it being in Gr.1, even with that sort of power, and it'd be the heaviest Gr.1 car to date by a notable margin if it were added. I, personally, live very close to Callaway's HQ, so I'm gonna try asking them if they know anything about this. Perhaps we could ask Zagato, as well, if they're anywhere nearly as receptive to questions as Callaway. But it still seems like quite the mystery! Maybe we'll see it in the next GT title, or even out of the blue in a future GT Sport update - but I really don't know.