The RT1 employed a monocoque chassis covered in a fibreglass body, a construction approach that kept the car exceptionally light at around 1,100 lb (500 kg). Power came from a 1.6 L (98 cu in) four-cylinder engine producing approximately 230 hp (170 kW), driving the rear wheels through a Hewland FT200 five-speed manual gearbox. The car was designed to accept engines from multiple suppliers, and over its competitive life it ran units from Hart, Cosworth, Toyota, and Volkswagen, making it adaptable to the requirements of different national championships and series rules. The straightforward engineering philosophy made the RT1 accessible to privateer teams and easier to maintain than more complex contemporary designs.
The RT1 made an immediate impact upon its debut. In 1975, Australian driver Larry Perkins took the car to victory in the Formula 3 European Cup, giving Ralt its first major success in the first season of the new chassis. The following year, 1976, the RT1 claimed victory in Formula 2 at the Nurburgring with German-Swedish driver Freddy Kottulinsky, and also won the German Formula 3 championship with Bertram Schäfer.
The 1977 season brought further success in Formula 3. Elio De Angelis, the Italian driver who would later compete in Formula 1, took the RT1 to championships in both Italy and Sweden, reinforcing the car's competitiveness across different national Formula 3 series.
The 1978 season was arguably the RT1's most dominant. Derek Warwick and Nelson Piquet each won one of the two British Formula 3 championships of that year, while Bertram Schäfer claimed the German, Swedish, and European Formula 3 titles. The breadth of championships taken in a single season across multiple countries underlined how thoroughly the RT1 had penetrated the Formula 3 market.
Success continued into 1979 and 1980 across Formula 3, Formula Atlantic, and Formula Super Vee categories. In Formula Atlantic alone, the RT1 accumulated 15 different championship titles, a remarkable record of dominance in a single formula that demonstrated both the car's fundamental speed and its suitability to the format's technical regulations.
In an unusual extension of its competition life, the RT1 was converted into an enclosed-wheel sports prototype configuration with full bodywork and used in the revived Can-Am series. In this form it differed substantially from its open-wheel origins. Results in Can-Am were modest compared to its open-wheel record — the RT1 managed one outright victory, at Mid-Ohio in 1979, along with four class wins and two further podium finishes in the series before being superseded by more purpose-built machinery.
The RT1 established the template for Ralt's approach to customer car manufacturing: light, adaptable, and reliable enough to win championships in the hands of amateur and professional teams alike. Its success across Formula 2, Formula 3, and Formula Atlantic simultaneously was exceptional for a single chassis design, and the 15 Formula Atlantic championships it accumulated stand as testament to how dominant a well-conceived design could be in the era before the market fragmented. The RT1 formed the foundation for subsequent Ralt models including the RT2, RT3, and RT4, each of which extended the manufacturer's competitive reach into new formulae. Ron Tauranac's philosophy of building straightforward, effective racing cars for customers found its clearest early expression in the RT1.