Mazda Cosmo Sport 110S, Frequently Asked Questions

What is the Mazda Cosmo Sport 110S?

The Cosmo Sport 110S is the world’s first production twin-rotor car, manufactured by Toyo Kogyo (now Mazda) from 1967 to 1972 in Hiroshima, Japan. It was powered by the 10A twin-rotor Wankel engine displacing 982cc, producing either 110hp (Series I, L10A) or 128hp (Series II, L10B). Just 1,176 were built, 343 Series I and 833 Series II, making it one of the rarest Japanese production cars in existence.

The Cosmo Sport was Mazda’s proof of concept for the rotary engine. Its success gave Mazda the confidence to develop the R100, RX-2, RX-3, and eventually the RX-7 and RX-8. Every rotary Mazda traces its lineage to this car.

What is the difference between Series I and Series II?

The two series are visually and mechanically distinct:

Series I (L10A, 1967-1968):

• 110hp 10A engine
• Four-speed manual gearbox
• Shorter wheelbase (2,200 mm)
• Lower, more compact body
• Distinctive split rear window
• 343 built
• The purist’s choice, rarer, more historically significant

Series II (L10B, 1968-1972):

• 128hp 10A engine (revised porting and compression)
• Five-speed manual gearbox
• Longer wheelbase (2,350 mm)
• Larger body with more interior space
• Single-piece rear window
• 833 built
• More usable, slightly more available

The Series I is generally more valuable due to its rarity and its status as the first of the breed. However, the Series II is the better car to drive, with more power, an extra gear, and improved refinement.

How much is a Cosmo Sport worth in Australia?

Prices depend entirely on condition and provenance:

• Restoration project (complete, needs everything): $100,000-180,000 AUD
• Running, presentable condition: $150,000-300,000 AUD
• Concours restored: $250,000-450,000+ AUD

Series I cars command a premium over Series II. Documented history, matching numbers, and known provenance add significant value. The market is so thin that each sale is essentially a private negotiation, there are too few transactions to establish a reliable price trend.

International auction results from Bring a Trailer, RM Sotheby’s, and Bonhams provide the best pricing guidance. Several Cosmo Sports have sold at auction in the US$100,000-250,000 USD range in recent years.

Was the Cosmo Sport sold in Australia?

No. The Cosmo Sport was sold exclusively in Japan. Every Cosmo Sport in Australia has been privately imported. Import documentation (SEVS approval, compliance, customs clearance) should be part of any Australian-resident car’s paperwork.

The car is right-hand drive (Japan drives on the left side of the road, same as Australia), so there is no conversion issue.

How does the 10A engine differ from the 12A and 13B?

The 10A is the smallest production twin-rotor Wankel engine Mazda built. Key differences:

Specification	10A	12A	13B
Displacement	982cc	1,146cc	1,308cc
Rotor Width	Narrower	Wider	Wider still
Apex Seal Width	2mm	3mm	3mm
Typical Power	110-128hp	130-145hp	135-255hp
Reliability	Marginal	Good	Excellent (pre-Renesis)

The key improvement from 10A to 12A was the wider apex seal, 3mm versus 2mm, which dramatically improved seal life and engine longevity. The 13B took the concept further with a larger rotor and housing, producing more power and even better durability. The 10A is the most fragile of the three, and parts are the hardest to source.

Can I daily-drive a Cosmo Sport?

Technically, yes. Practically, no. The Cosmo Sport is a 50-plus-year-old car with irreplaceable body panels, unavailable parts, and an engine that requires specialist knowledge to maintain. Using it as a daily driver would accelerate wear on components that cannot be replaced, expose the car to accident risk it cannot afford, and subject a museum-quality vehicle to conditions it was never designed for.

The Cosmo Sport is a low-mileage weekend and event car. Start it regularly, drive it often enough to keep the seals lubricated and the systems circulating, but keep the kilometres modest. If you want a rotary for daily use, buy an RX-7 or RX-8.

What fuel does the Cosmo Sport use?

Premium unleaded, 98 RON. The 10A’s compression ratio and combustion characteristics require high-octane fuel. Do not use E10 or higher-ethanol blends unless the fuel system has been upgraded with ethanol-compatible materials, the original rubber hoses and carburettor components will degrade rapidly with ethanol exposure.

The oil metering pump injects two-stroke oil into the combustion chamber to lubricate the apex seals. If the pump is functioning, no premix is needed (though many owners premix as additional insurance). If the pump is disconnected, premix at approximately 1:200 (two-stroke oil to fuel).

How do I find parts for a Cosmo Sport?

With difficulty. Here are your sources:

• Rotary engine internals (apex seals, bearings, gaskets): Some components are shared with or adaptable from later rotary engines. Australian specialists like Atkins Rotary (Brisbane), PAC Performance (Sydney), and Promaz (Melbourne) stock rotary engine parts and can advise on compatibility.
• Cosmo-specific parts (body, trim, interior, glass): NOS (new old stock) from Japanese dealers and collectors. Yahoo Auctions Japan is a primary source. Japanese Cosmo Sport clubs maintain parts networks.
• Reproduction parts: Virtually non-existent. The production volume was too low to justify reproduction tooling.
• Fabrication: For many parts, custom fabrication by a specialist is the only option. Budget accordingly.

Build a relationship with a Japanese Cosmo Sport enthusiast or dealer. They are your lifeline for parts sourcing.

What is the Marathon de la Route, and why does it matter?

The Marathon de la Route was an 84-hour endurance race held on the Nurburgring Nordschleife. In 1968, Mazda entered two Cosmo Sports, the car’s first major international motorsport outing. One retired, but the second car finished fourth overall, behind three Porsche 911s.

This result was enormously significant. It proved the 10A engine could survive 84 hours of continuous high-speed running on one of the world’s most demanding circuits. It established Mazda’s motorsport credentials in Europe. And it gave the company the confidence to develop the rotary-powered racing programme that would culminate in the RX-3’s dominance at Bathurst and the 787B’s legendary victory at Le Mans in 1991.

Is the Cosmo Sport a good investment?

The Cosmo Sport has appreciated steadily for the past two decades and shows no signs of reversing. Fewer than 1,200 were built, attrition continues to reduce that number, and demand from collectors of significant Japanese cars is growing. The car has genuine historical importance, it is the first of its kind, and that distinction supports long-term value.

However, investment should not be the primary motivation for buying a Cosmo Sport. The car demands significant ongoing expenditure for storage, maintenance, insurance, and parts. It is an illiquid asset, selling one requires finding the right buyer, which may take months or years. Buy a Cosmo Sport because you understand what it is and what it represents. If it also appreciates in value, consider that a bonus.

Who should I talk to in Australia about Cosmo Sports?

The Australian rotary community is tight-knit and knowledgeable:

• Rotary Engine Club of Australia: The primary club for rotary enthusiasts. Members include people with deep knowledge of early rotary models.
• Atkins Rotary (Brisbane): Rotary engine specialists who have worked on everything from 10A to 20B engines.
• PAC Performance (Sydney): Primarily known for high-performance rotary work, but with broad rotary knowledge.
• Promaz (Melbourne): Rotary specialists with engine building and tuning expertise.
• RX7Club.com and AusRotary forums: Online communities where Cosmo Sport owners and enthusiasts share knowledge.

If a Cosmo Sport comes up for sale in Australia, the rotary community will know about it. Stay connected.

How many Cosmo Sports survive today?

No definitive registry exists, but estimates suggest 300-500 survive worldwide, with the majority in Japan. Fewer than a dozen are believed to be in Australia. The survival rate is relatively high for a 1960s Japanese car, because the Cosmo Sport has been recognised as significant since the 1980s, and owners have generally treated them with care.

The Cosmo Sport is increasingly appearing at concours events and major auctions, which helps track surviving examples. The Japanese Cosmo Sport owners’ club maintains the most comprehensive registry.