The Pantera road car was designed by Tom Tjaarda of Carrozzeria Ghia and debuted at the 1970 New York Motor Show. De Tomaso used a mid-mounted Ford 351 Cleveland V8 and a ZF transaxle, giving the car strong power and a fundamentally sound layout for competition. The road-going GTS variant, introduced in the spring of 1972 for the European market, was developed explicitly with Group 3 racing in mind and received a higher-compression engine rated at 350 PS at 6,000 rpm, wider wheels, ventilated disc brakes, and revised gear ratios.
De Tomaso offered competition Panteras built to Group 3 specifications between 1972 and 1984, supplying cars to private customer teams on special order. Thirty such cars were constructed. Group 3 rules were highly restrictive and permitted only limited departures from production specification, which shaped every detail of the conversion.
The Group 3 Panteras used Campagnolo wheels — 15×8 inches at the front and 15×10 inches at the rear — along with adjustable Koni shock absorbers, racing brakes (not permitted until 1975), and mandatory safety equipment including a roll bar, plexiglass windows with cutouts, a fire extinguisher, and bucket seats. Engine modifications centred on a reinforced camshaft, a larger 10-litre oil sump, and a Holley racing four-barrel carburetor, bringing power to approximately 336 PS. The drivetrain used a five-speed close-ratio gearbox, a heavy-duty single-plate clutch, and a limited-slip differential. With long-ratio gear selections, the Group 3 cars were reportedly capable of reaching 280 km/h.
The competitiveness of the Group 3 Pantera had a notable side effect: it was credited as a direct factor in Porsche accelerating the development of the more powerful 911 Carrera RS and Carrera RSR. A serious incident at the Charade circuit in 1973 prompted De Tomaso to develop reinforced wheel hubs, which were subsequently approved for Group 3 use.
Following the introduction of the Group 3 car, De Tomaso launched a more extensively modified Group 4 version in 1972. British engineer and driver Mike Parkes, who had previously developed racing cars for Ferrari, was engaged to lead the project.
The Group 4 car retained the road car's steel monocoque chassis as mandated by regulations, but the double-wishbone suspension was substantially reworked to accommodate wider Campagnolo wheels and to improve circuit handling. Koni adjustable dampers were used throughout. Larger ventilated brakes from Girling and a quick-ratio steering rack were fitted. The standard steel bodyshell was modified with aluminium doors, front lid, and engine cover, along with flared fibreglass wheel arches, while plexiglass windows replaced glass and holes were drilled through the chassis to reduce weight. The final car weighed 1,100 kg.
The engine remained based on the Ford 351 Cleveland V8 but received bespoke aluminium cylinder heads, TRW forged pistons, titanium valves, and a larger oil sump. Initially fitted with a single Holley Racing 1150 CFM four-barrel carburetor, this was later replaced by four Weber carburetors and a revised intake. The compression ratio was raised to 12.0:1. A spaghetti-style exhaust system similar to that used on the Ford GT40 was adopted. The engine was claimed to produce 507 PS, though the cars were typically raced at around 446 PS at 7,000 rpm, rising to 477 PS with the Weber 850 CFM units. The ZF five-speed close-ratio gearbox was retained.
The first Group 4 Panteras were entered in the 1972 24 Hours of Le Mans. Problems quickly became apparent: the engine proved unreliable and the car was subject to a weight penalty that pushed total weight to 1,250 kg, reportedly set high due to Porsche's influence on the governing body. Chassis rigidity also caused concern. Engine sourcing was complicated by Ford's reluctance to supply motors for the racing programme; De Tomaso turned to US-based private engine builder Bud Moore to address the shortfall. A total of 14 Group 4 cars were built, and some Group 3 cars were subsequently converted to Group 4 specification by private teams.
From 1976 to 1981, Group 5 Panteras were raced by private teams, typically converted from earlier Group 3 or Group 4 cars. These conversions principally involved wider body panels without significant mechanical or structural changes.
Two cars were, however, subjected to more extensive modification. The first, carrying chassis number 001, was built from a new chassis by Italian racing team Sala and Marveti and later converted to Group C specification in 1983. The second, chassis 1603, had been campaigned in the United States by Hugh Kleinpeter before being substantially reworked and later converted to IMSA GTP specification. Both cars proved uncompetitive in their respective categories.
The racing Pantera programme demonstrated that an Italian-American hybrid could be made genuinely competitive in international GT racing at a fraction of the budget available to the major factory teams. The 30 Group 3 cars and 14 Group 4 cars collectively represent one of the more ambitious privateer racing programmes of the 1970s, notable for the seriousness with which De Tomaso approached the homologation and development of what began as a grand tourer sold through American Lincoln-Mercury dealerships.