Overview

The Mazda Cosmo Sport 110S (1967-1972) is the car that started it all. The world's first production twin-rotor vehicle, beating the NSU Ro 80 to market by a matter of days. This is not a car you stumble across at a swap meet. It is a museum piece, a landmark in automotive engineering, and one of the rarest Japanese cars on the planet. Fewer than 1,200 were built across two series, and the number surviving today is a fraction of that.

For the Australian buyer, the Cosmo Sport is borderline unobtainable. Right-hand drive examples exist, Japan drove on the left, so the steering is correct for Australian roads. But finding one for sale, in any condition, is a once-in-a-decade event. Most are in Japan, held tightly by collectors. A handful have made their way to Australia and the United States. If you are reading this guide because you have found one for sale, you already know what it is and what it is worth. This guide is about making sure you buy the right one.

The Cosmo Sport came in two series. The L10A (Series I, 1967-1968) is the earlier, rarer, more visually distinctive car with a shorter wheelbase, a lower roofline, and a split rear window. It produced 110 horsepower from its 982cc 10A twin-rotor engine. The L10B (Series II, 1968-1972) had a longer wheelbase, more conventional rear window, a fifth gear, and 128 horsepower from a revised 10A. Both are extraordinarily rare. The Series I is the collector's choice; the Series II is marginally more usable.

Prices start at $150,000 AUD and escalate rapidly. Concours examples have traded above $300,000 internationally. At these numbers, provenance, originality, and documentation matter enormously.

What to Look For

Engine, 10A Twin-Rotor

The 10A is the engine that proved Mazda's rotary concept. It is a 982cc twin-rotor Wankel producing either 110hp (L10A) or 128hp (L10B). The engine is small, light, and surprisingly torquey for its displacement. It is also the oldest production rotary engine design, and it shows its age in terms of durability compared to later 12A and 13B units.

Apex seal wear is the defining issue. The 10A's apex seals are narrower than later designs, and the materials science was in its infancy. A healthy 10A should produce consistent compression across all faces, a compression test is non-negotiable before purchase. You need a rotary-specific compression tester. Readings should be above 6.5 kg/cm2 and within 0.5 kg/cm2 of each other across all faces. Low or uneven readings mean a rebuild is imminent.

Cold starting is notoriously difficult on the 10A. The engine uses a manual choke system, and the apex seals need heat to expand and seal properly. If the car takes more than a few cranks to fire when cold, the seals may be worn, or the ignition and fuel system need attention. Expect to learn a starting ritual.

Oil metering pump, the 10A relies on an oil metering pump to inject two-stroke oil into the combustion chambers to lubricate the apex seals. If this pump has failed or been disconnected, the seals are living on borrowed time. Check that the pump is present, connected, and functioning. Many owners run premix (adding oil directly to the fuel) as insurance, but the metering pump should work regardless.

Cooling system, early rotaries run hot. The Cosmo Sport's cooling system was adequate for 1967 but marginal by modern standards. Check for overheating history, coolant condition, radiator condition, and thermostat function. An upgraded aluminium radiator is a sensible modification, but originality purists will want the factory unit.

Bodywork

The Cosmo Sport's body is hand-finished steel, and replacement panels do not exist as off-the-shelf items. Any significant rust or accident damage requires hand fabrication by a specialist panel beater. This is not a car where you can order new guards from a catalogue.

Rust areas to inspect:

• Sills and rocker panels: The lower body edges collect moisture. Inspect from underneath.
• Floor pans: Lift the carpets. Any perforation is a serious issue.
• Wheel arches: Rear arches are prone to corrosion from road spray.
• Boot floor: Check for moisture intrusion.
• Around the windscreen: The windscreen rubber seals deteriorate, admitting water.

Panel fit: Because these cars were largely hand-assembled, panel gaps are not perfectly uniform from the factory. But large gaps, misaligned panels, or evidence of filler indicate accident repair. Run a paint depth gauge over the entire car.

Glass: The Cosmo Sport uses unique curved glass. Replacement windscreens are virtually impossible to source. Cracked or chipped glass is a significant problem.

Interior

The Cosmo Sport's interior is space-age for 1967, a distinctive dashboard with a prominent tachometer, unique seats, and a design language that reflects the car's futuristic intent. Interior trim parts are unobtainable as new items. Everything you see must be original or professionally restored.

Seats: Check the seat frames for rust and the upholstery for deterioration. Retrimming in the correct materials requires sourcing the right fabric and finding a trimmer who understands the car.

Dashboard and instruments: Ensure all gauges work. The tachometer and speedometer are model-specific. Non-functioning instruments reduce the car's value significantly, and repair requires a specialist.

Switches and electrics: Test every switch, light, and electrical function. Wiring harness replacement or repair on a Cosmo Sport is an exercise in patience and fabrication.

Transmission

The L10A has a four-speed manual gearbox; the L10B has a five-speed. Both are adequate for the engine's output. Check for smooth engagement in all gears, no grinding on downshifts (synchro wear), and no excessive play in the linkage. Gearbox parts are extremely scarce.

Suspension and Brakes

The Cosmo Sport uses a front de Dion tube arrangement (Series I) or independent front suspension (both series use a live rear axle on the L10B, verify for the specific car). The suspension is simple and robust, but bushings will be worn after 50+ years. Replacement parts must be custom-manufactured or sourced from Japanese specialists.

Brakes are front disc, rear drum. Check disc condition, pad material, and brake line integrity. Convert to braided stainless lines for safety.

Provenance and Documentation

At Cosmo Sport prices, provenance is everything. You need:

• Chassis number verification: Confirm the chassis number matches all documentation. The Cosmo Sport chassis number is stamped on the firewall.
• Production records: Mazda Japan has records. A serious seller will have contacted Mazda to verify the car's history.
• Import documentation: If the car was imported to Australia, you need the SEVS (Specialist and Enthusiast Vehicle Scheme) approval documentation, compliance plate, and customs clearance.
• Restoration records: If restored, detailed photographic records of the work, receipts from specialists, and documentation of any parts sourced.
• Previous ownership: A documented chain of ownership adds confidence.

Price Guide (Australia, 2026)

Series I (L10A, 1967-1968)

• Restoration project (complete, needs full rebuild): $120,000-180,000+
• Running, presentable: $200,000-300,000
• Concours restored: $300,000-450,000+

Series II (L10B, 1968-1972)

• Restoration project: $100,000-150,000
• Running, presentable: $150,000-250,000
• Concours restored: $250,000-350,000+

These prices are indicative. The Cosmo Sport market is so thin that each car is essentially a unique transaction. International auction results provide the best guidance, Bring a Trailer, RM Sotheby's, and Bonhams have all sold Cosmo Sports in recent years.

Running Costs

Parts availability: Terrible. Almost everything is NOS (new old stock), used, or custom-fabricated. Japanese Cosmo Sport clubs and specialists like RE Amemiya and Mazdaspeed Heritage (if you can contact them) are the primary sources. Some engine internals (apex seals, bearings, gaskets) can be sourced from rotary specialists like Atkins Rotary or Promaz in Australia, as the 10A shares some dimensions with later rotary engines. But many components are Cosmo-specific and effectively unobtainable.

Servicing: You will not take this car to a general mechanic. You need a rotary specialist, and even then, the Cosmo Sport's specific systems are unfamiliar to most. Budget for a specialist who is willing to learn the car alongside you.

Fuel: The 10A drinks premium unleaded (98 RON) and consumes two-stroke oil through the metering pump. Fuel economy is approximately 15-18 L/100 km in mixed driving.

Insurance: Agreed-value classic car policy, mandatory. Standard insurance will grossly undervalue the car. Budget $2,000-5,000/year depending on agreed value and usage.

The Verdict

The Cosmo Sport is not a car you buy to drive on weekends. It is a car you buy because you understand its significance, because you have the resources to maintain it, and because the opportunity to own one may never come again. It is the genesis of Mazda's rotary programme, without this car, there would be no RX-7, no RX-3, no Bathurst legend. Every rotary that followed stands on the Cosmo Sport's shoulders.

If you find one, engage an independent specialist to inspect it before committing. Fly to wherever the car is. Spend a full day going over it. Verify every claim. And if it checks out, buy it. They are not making any more.