They selected one of the most grueling tests in Europe to prove the reliability of the rotary engine, the 84-hour Marathon de la Route at the legendary Nürburgring circuit in Germany.

One major change to the cars' 10A engines was the addition of a novel side- and peripheral-port intake system: A butterfly valve switched from the side to the peripheral port as RPM increased.

The Series I/L10A Cosmo was powered by a 0810 two-rotor engine with 982 cc of displacement and produced about 110 hp (thus the 110S name used in export markets).

This Cosmo was good for over 120 mph (193 km/h) and could accelerate to cover a quarter-mile (400 m) in 15.8 s. Visual changes included a larger grille under the front bumper with two additional vents to each side of this "mouth".

A 1970 Mazda Cosmo Sport Series II L10B Coupe sold in January 2015 for US$110,000 inclusive premium at auction at Bonhams.

The anti-pollution label reflected that the cars were able to meet the strict, 1976 Japanese emissions standards, thanks to the installation of a thermal reactor which kept hydrocarbon levels down.

[5] The CD Cosmo/RX-5 series was positioned as a personal luxury car, with a focus on comfort and high equipment levels rather than outright sportiness.

Inspired by the US market, in particular the 1970s era Lincoln Continental, a notchback coupé model called the Landau appeared in early 1977.

In Europe, the RX-5 saw very little competition in the rotary-engine equipped market, with the introduction of the short-lived Citroën GS Birotor, as well as any remaining NSU RO80 sedans.

The Cosmo was Mazda's largest rotary-powered coupé, based on the LA series Mazda Luce floor pan and mechanics, but slightly heavier due to body design and more luxurious appointments, including a five-link rear suspension and rear disc brakes.

This series Cosmo was joined by the short-lived Mazda Roadpacer, a large, heavy sedan powered only by a rotary engine.

After Mazda noted a space for a more powerful piston-engined derivative, as rotary sales were slowing down because of their high fuel consumption, the bigger Cosmo 2000 with 110 PS (81 kW) became available in March 1977.

The range was facelifted in October 1983, at which time the fuel injected 13B-SI engine was introduced and the four-door hardtop switched from pop-up to fixed headlights.

When the FC series Mazda Savanna RX-7 was introduced in 1986 internationally, this series Cosmo coupe retained its top position as Mazda's largest rotary powered personal luxury car, with a comfortable backseat, trunk, and every luxury amenity available, while adopting the retractable headlights from the RX-7.

The HB Cosmo and Luce names were used in Japan, with the 929 being the export version (which was not available with the rotary engine options).

Not all two-door 929 models used the FET, most used other variants of the FE engine, either Carburetor or EGI with optional four-speed automatic transmission.

The triple rotor 20B had 2 litres (1962 cc) of displacement, making it the largest capacity rotary offered for sale by Mazda.

[12] The instrumentation used a LCD display rendering analog gauges with indicator needles that "floated" and using vivid colors for various functions.

[13] With over 380 N⋅m (280 lb⋅ft) of torque available at just 1,800 rpm, the Cosmo could launch from standstill to freeway speeds quickly; however, this came at the expense of heavy fuel consumption.

The JC Cosmo was expensive even by today's standards, as Mazda still has not matched the sales price of this car some 22 years later for anything else in its range.

The availability of power and speed in the Cosmo appears extravagant in its intended market of Japan once it becomes understood that most of the driving environment consists of two-way streets that are usually zoned at 40 km/h (25 mph) or less,[14] as mentioned in the article Speed limits in Japan The Cosmo was manufactured from February 1990 until September 1995, and gathered a total of 8,875 sales.