The Testarossa was conceived to address the shortcomings of the 1981 512 BBi, primarily an overheating cabin caused by plumbing that ran the length of the car between the front radiator and the mid-mounted engine, and a lack of luggage space. The solution was to relocate the radiators from the front of the car to twin side units positioned near the rear engine, eliminating the long hot plumbing runs and dramatically reducing cabin heat. This layout change necessitated large side air intakes, which became the car's most recognisable styling feature.
The Pininfarina design team — led by Leonardo Fioravanti and including designers Ian Cameron, Guido Campoli, Diego Ottina, and Emanuele Nicosia — turned the functional requirement into a statement. Wide horizontal strakes, often called cheese graters, spanned the doors and rear flanks to cover the side intakes while complying with regulations in several countries that prohibited large open apertures on road cars. The strakes made the rear of the car wider than the front — 1,976 mm overall — improving stability. The car also dispensed with a rear spoiler, achieving a drag coefficient of 0.36, notably lower than the Lamborghini Countach's 0.42.
The name Testarossa pays homage to the 1957 World Sportscar Championship-winning 250 Testa Rossa. Testa Rossa translates as "red head" in Italian, referring to the red-painted cam covers on both cars' 12-cylinder engines.
The Testarossa premiered at the 1984 Paris Auto Show. Its engine is a naturally aspirated 4.9-litre (4,943 cc) longitudinally-mounted flat-12 of type Tipo F113, featuring DOHC four-valve cylinder heads with a dry-sump lubrication system. Output was 390 PS (287 kW; 385 hp) at 6,300 rpm and 490 N·m (361 lb·ft) of torque at 4,500 rpm. The car accelerated from 0 to 100 km/h in 5.8 seconds and reached a top speed of approximately 290 km/h. A five-speed manual gearbox drove the rear wheels.
Early cars used distinctive 16.33-inch magnesium single-bolt knockoff wheels with Michelin TRX tyres. From the 1986 model year, standard 16-inch wheels replaced these, and from mid-1988 the suspension was redesigned and five-bolt wheels were adopted. A single driver's-side door mirror on early cars was a signature detail; US-market cars received a second mirror from 1987. The Testarossa was never entered in competition, unlike its predecessor.
The 512 TR debuted at the 1991 Los Angeles Auto Show as a substantially re-engineered successor. The Tipo F113 D flat-12 gained Nikasil cylinder liners, a new Bosch engine management system, larger intake valves, and a revised exhaust system, raising output to 422 hp (315 kW) at 6,750 rpm and 491 N·m of torque at 5,500 rpm. The 512 TR accelerated to 100 km/h in 4.8 seconds and reached 313.8 km/h. Engine and gearbox positioning was revised to improve the centre of gravity, and handling was further sharpened with quicker steering, lower-profile tyres on 18-inch wheels, and revised damper settings. The interior was also updated, with a restyled centre console and relocated climate controls.
The F512 M was revealed at the 1994 Paris Auto Show and was the final variant. Only 501 cars were built, of which 75 were for North America, all as 1995 model year cars. The Tipo F113 G engine, fitted with titanium connecting rods and a revised crankshaft 7.26 kg lighter than the units they replaced, produced 434 hp (324 kW) at 6,750 rpm with a 7,500 rpm rev limit. The F512 M reached 315 km/h and covered the standing kilometre in 22.7 seconds. External changes included the replacement of pop-up headlamps with fixed square units and restyled rear tail lamps and bumpers. The F512 M was the last Ferrari to use a flat-12 engine.
A single official convertible Testarossa Spider (chassis number 62897) was built in 1986 on commission for Fiat chairman Gianni Agnelli to commemorate his 20 years at the company. Finished in Argento Nurburgring silver with a white soft top, it featured a solid silver Ferrari logo on the hood. The car sold at auction in 2016 for US$1.3 million.
The Ferrari Mythos concept (1989) used Testarossa mechanical components beneath an entirely new open body, powered by the same flat-12 engine producing 390 hp. Designer Luigi Colani adapted a Testarossa for the Testa d'Oro land speed record attempt in 1989; fitted with a turbocharged 5.0-litre engine producing 750 hp, it broke its class record in 1991 at 351 km/h.
The Ferrari FX, a special-order car built by Pininfarina for the Sultan of Brunei, used the F512 M flat-12 engine paired with a seven-speed sequential gearbox sourced from the Williams Formula One team. Between seven and nine examples were produced.
The Testarossa became one of the most recognised cars of the 1980s largely through its role in Miami Vice from the show's 1986 season onward, though it was a white car associated with the show's aesthetic rather than the series' initial black Ferrari. Enzo Ferrari personally gifted a silver 1989 Testarossa to actor Don Johnson, who was a fan of the programme. The car also appeared as the player's vehicle in Sega's Out Run franchise, cementing its association with the decade's aspirational pop culture. Notable owners included Elton John, Rod Stewart, Michael Jordan, Mike Tyson, and Formula One driver Gerhard Berger.