Some cars leave a paper trail; the Dallara GP2/05 left a name and a place in Dallara's list. What follows is what can be said with a source behind it. Giampaolo Dallara drew it.
The story
The Dallara GP2 cars are a set of racing cars developed by Italian manufacturer Dallara for use in the GP2 Series, a feeder series for Formula One. After twelve years of service, the GP2 cars were retired in 2017 and succeeded by the Dallara F2 cars, following Liberty Media's acquisition of the GP2 Series and subsequent rebrand into the FIA Formula 2 Championship.
What is underneath
612 bhp @ 10,000 rpm is the published figure. It weighs 585 kg. Work it out per tonne and you get about 1046 horsepower — hypercar territory, where the limiting factor is the tyre, not the engine. These are manufacturer figures carried by Wikipedia and Wikidata, not road-test measurements.
Its place in the line
Its family tree is legible: it took over from the Lola B02/50; its successor was the Dallara GP2/08. Nearby in the Dallara catalogue sit the Dallara 320 and the Dallara F191.