The Eagle project grew from Dan Gurney's ambition, formed while driving for the Brabham works team, to build and campaign his own racing machinery. Together with Carroll Shelby and backed principally by the Goodyear Tire and Rubber Company, Gurney co-founded All American Racers in Santa Ana, California, in 1964. Because Formula One's engineering centre of gravity lay in Britain, a subsidiary operation named Anglo American Racers was established in Rye, East Sussex, close to Harry Weslake's engine development plant.
Gurney hired former Lotus designer Len Terry, who had recently produced the 1965 Indianapolis 500-winning Lotus 38, to design a chassis capable of competing on both Formula One road courses and American oval circuits simultaneously. The result — the Mk1 for F1 and the Mk2 for Indy — shared a riveted aluminium monocoque central section with an unstressed engine mounted behind the driver. The bodywork lines were famously clean and graceful, featuring a distinctively beaked radiator opening at the nose and a single white dorsal stripe over the dark Imperial blue livery that served as an elegant interpretation of the United States national racing colour.
Suspension was relatively conventional — lower wishbone and single top link at each corner, driving inboard spring and damper units — but the overall design was advanced enough to be immediately competitive once its intended engine arrived.
The car was designed from the outset around a new 3.0-litre V12 developed by Aubrey Woods at Weslake Engineering, a project originally seeded by Shell Oil research funding that Gurney became aware of through his BRM days. Extrapolating from a promising 500cc two-cylinder test unit, Gurney commissioned Weslake to build a full Grand Prix V12 with a target output approaching 450 horsepower.
Because the Weslake engine was not ready at the start of the 1966 season, the first Mk1 chassis ran with an older 2.7-litre Coventry Climax inline-four. Once the V12 appeared — introduced at the 1966 Italian Grand Prix — it delivered a distinctive high-revving scream and an immediately arresting turn of speed, producing around 360 bhp in early form and eventually exceeding 400 bhp by the end of 1967, putting it on terms with the Ferrari and Honda V12s and the new Cosworth DFV. However, the engine was constructed on surplus machine tools dating from the First World War, meaning tolerances and parts interchangeability were poor. A design flaw in the oil scavenging system caused oil to pool in the sump, reducing power after three or four laps of hard running — an issue Gurney described as "taking the edge" off the engine. These reliability problems would prove costly throughout the car's racing life.
A fourth chassis, numbered 104, was constructed using advanced materials including titanium components and magnesium sheet panelwork to reduce weight. Known as the Ti-Mag Car, it was the lightest and fastest of the four Eagles built. Gurney, who witnessed Jo Schlesser's death in a magnesium fire at the 1968 French Grand Prix, later remarked that racing in 104 was like "driving a Ronson cigarette lighter."
The Eagle Mk1 made its championship debut at the 1966 Belgian Grand Prix, a single entry for Gurney that failed to finish. Early points came later in the season at the French and Mexican Grands Prix, both times with the older Climax-engined car. For 1967, AAR ran all cars on Weslake power and the campaign took on a frustrating character: Gurney and teammate Bruce McLaren qualified in the front two rows of the grid at eleven of the season's eleven Grands Prix, yet only two cars finished races across the entire season.
The season's defining moment arrived at the 1967 Belgian Grand Prix at Spa-Francorchamps. Gurney drove Ti-Mag chassis 104 to an outright victory — the first American triumph in a Grand Prix since Jimmy Murphy's Duesenberg win at the 1921 French Grand Prix, and a result that made Gurney only the second person in Formula One history (after Jack Brabham) to win a World Championship race in a car bearing his own name. A non-championship victory earlier in the year at the Race of Champions at Brands Hatch had already signalled the car's potential.
By 1968 Anglo American Racers was running short of funds. Development of the Mk1 stopped as resources were redirected toward a planned successor, the Mk6, which was never completed. Gurney persisted with the older car for the first half of 1968, but the best result was a single ninth-place finish. AAR subsequently purchased a McLaren M7A and scored a handful of points with it before closing the Formula One programme at the season's end. The final appearance of an Eagle Mk1 in World Championship racing came at the 1969 Canadian Grand Prix, where privateer Al Pease entered the original Climax-engined chassis 101 — the car earning the distinction of being the only entry in Formula One history to be disqualified for travelling too slowly.
Despite being universally known as the T1G in the wider motorsport world, Dan Gurney confirmed that the designation was never official. The car was simply the Eagle Mark 1, with the four F1 chassis numbered 101 through 104. The Indianapolis sister car was the Mk2, subsequent Indy designs took Mk3 and Mk4 designations, and a Formula A car adapted from the Mk4 was the Mk5. The Mk6 Formula One successor existed only as a project.
The Eagle T1G represents the high-water mark of American ambition in Formula One grand prix construction during the 1960s. Its single World Championship victory remains a landmark in the sport: the only winning car built in the United States, achieved by the driver who built it. The car's combination of aesthetic elegance and genuine pace — undermined only by chronic unreliability — has secured it an enduring reputation as one of the great might-have-beens of the 1.5-litre-to-3-litre transition era.