The ACR-X is the ZB II taken off the road entirely: a turn-key, non-street-legal race car built for 2010 and the one-make Dodge Viper Cup. Factory long-tube headers and a low-restriction exhaust lifted the 8.4-litre V10 to 640 hp and 605 lb-ft, roughly 160 lb was stripped out (landing near 3,200–3,260 lb), and it gained Viper Competition Coupe safety equipment — a full roll cage, race seat and fuel cell — plus more downforce than the street ACR.
It is the fastest ZB II by a wide margin: 0–60 mph in about 3.3 seconds and a Nürburgring Nordschleife lap of 7:03.06 (set Feb 2012, after production ended). Only around 50 were built — some sources say fewer — and because it is not road-legal it is priced and used as track equipment, not a road Viper.
No. It is a turn-key, track-only race car built for the one-make Dodge Viper Cup — no road registration. It came with Viper Competition Coupe safety equipment (roll cage, race seat, fuel cell) rather than road amenities.
Roughly 40 hp more: 640 hp and 605 lb-ft, versus 600 hp / 560 lb-ft on the street cars, thanks to factory long-tube headers and a low-restriction exhaust. It is also about 160 lb lighter than a standard Viper.
Around 50, though the exact number is disputed — some sources report closer to 43. All were built for 2010 as Viper Cup race cars.
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