The Mazda R100 was first seen in Japan in 1967 at the Tokyo Motor Show, and was originally called the RX85. Subsequently it was introduced in Japan in April 1968. where it was called the FAMILIA PRESTO ROTARY COUPE, and sold in overseas markets as the R100. There was also a 4 door version (sold from April 1970) known as the FAMILA ROTARY SS. The "original shape" of the R100 was sold April 1968 until 1973.

At this time the shape was changed after 1973, which was still called the FAMILIA PRESTO (model code FA3TS), and in Japan as the FAMILIA PRESTO ROTARY COUPE until 1973. R100 coupes and sedans were powered by a 10A twin distributor engine, that developed 100 BHP and 98 lb-ft of torque. All markets except the USA used the 0820, (detuned Cosmo sport 0813). The USA models (sold April 1969-1972) used the revised 3877 with thermal reactor for lower emissions

The Cosmo Sport, or 110S, was never intended for mass production, nor was it designed for it. Even in production, bodies moved down the "assembly line" on hand trucks rather than on an automated line. If Mazda were to recoup its investment in the rotary engine, it would have to sell rotary-engined cars at rates greater than 20 per month. The easiest way to do this would be to put the rotary in a car already in production with a conventional piston engine. And that's exactly what Toyo Kogyo did. Detuning the 10A engine with milder port timing and a smaller bore carburetor, TK put the resulting 10A, engine code 0820, into the Familial coupe, which otherwise came with a 1200cc piston engine.

The 0820 version of the 10A engine had a number of changes that were made to reduce cost for volume manufacture. Instead of the Cosmo engine's all aluminum construction, the R100's rotary had cast iron side housings. The eccentric shaft, chrome-molybdenum steel in the Cosmo, was chrome steel for the R100. Exhaust was routed directly out of the engine, instead of being routed through the "cool" side of the engine, as Mazda engineers relied instead on coolant circulation for balancing heat distribution within the engine. The R100's engine was otherwise similar to the Cosmo's, though with horsepower reduced to 100bhp (at 7000rpm) and torque to 98lb-ft @ 3500rpm

A US version was developed in mid-1968, when the 10A engine gained a thermal reactor and air injection into the exhaust ports for emissions control. The engine was given the code number 3877 and the model released in April 1969 (though Toyo Kogyo wouldn't establish a US sales organization and begin imports until mid-1970) With federal smog equipment, rated horsepower of the 10A remained the same, but torque dropped to 92lb-ft @ 4000rpm.

With the exception of the rotary engine, the R100 was a typical Japanese small car of the era, comparable to a Corolla or Datsun 1200 in size. In the US it was sold as the Mazda 1200, as coupe, sedan and wagon versions, powered by a four-cylinder engine. The sedan Familial was rotarized in April 1970 and sold in Japan as the Familial Rotary SS. However, the sedan version of the car was never sold state side with rotary power.

The coupe R100 had a unit steel body, with a front-engine/rear-drive configuration. Front suspension was MacPherson strut; the rear was Live Axle on leaf springs. A Road & Track road test noted, however, an " extremely good freeway ride " the result of soft springs, and " good steering characteristics but not impressive grip " The R100 came standard with radial tires, but they were a diminutive 145 set. width on 14in rims. An engine fault with the original test car led to a re-test in a later issue, yielding an 18.6s 1/4 mile, a top speed of 99mph, and fuel economy of 21.6mpg in "normal driving."

Road & Track loved the four-speed manual transmission, and marveled at how " Smooth and Silent '' the R100 was Strangely so, for this sort of car usually has an inline 4 banger .... Above 3000rpm it begins to feel quite strong and from there on up it gets smoother and smoother while developing a mild intake snarl." They called the engine " positively intoxicating " and as rotary drivers through the years would note, felt it was a shame to have to shift at the 7000rpm redline. Said Road & Track, " This rev limit is what Mazda set to insure that the rotor apex seals have a long and healthy life If we'd been willing to go on to, say, the 8000rpm that is marked on the tachometer, we'd have knocked some tenths off the acceleration times ... " The magazine summed it up with the assessment that " the Mazda R100 coupe is one helluva nice little car"

On the other hand, at $2,495 (West coast), the R100 was considerably more expensive than its piston-powered counterparts, though the price included white wall tires and wheel covers! It was sold on the US market alongside its piston-powered alter ego and the larger RX-2 and its 1800cc piston engine counterpart. At home, the short-lived R130 Luce Rotary coupe combined the front-wheel drive and the 13A rotary engine; that car and engine lasted from 1970-72. Unlike the purpose-built Cosmo Sport. the Familial was a conventional design in production since 1967 and into which a rotary engine was installed. It should have been no surprise, then, when Toyo Kogyo discontinued the R100 in the US in early 1972 (though continuing it in Japan though 1973). What is perhaps surprising in retrospect is that tile R100 was superseded by another conventional chassis which was sold with either a rotary or piston engine with only minor changes in configuration. The initial success of the RX-3 didn't make it seem like a mistake at the time though.

What to Look For

With its status as the first volume production rotary engined car, the Mazda R100 is a landmark in automotive history. That doesn't guarantee universal appreciation, however, even among car buffs. It qualifies as a collectible more as a curiosity than for popularity. Because it was sold almost exclusively in the Pacific Northwest, the R100 is a rarity elsewhere in the country and relatively unknown, except among Mazda fans. That doesn't mean, however, that an R100 can't be found anywhere else, even on the east coast or deep south.

The R100 you find, however, will likely not be a creampuff. Indeed, you'll be lucky to find one running, particularly with the original engine. Engine swaps from the 10A to the 12A or 13B are possible. The bad news is that they are not particularly easy. The 12A and 13B bell housing bolt patterns are different from the 10A's, so it may be easier to replace the entire engine and transmission as a unit. The later transmissions will be a snug fit in the transmission tunnel however Rebuilding the 10A motor won't be easy as parts are scarce, if not absolutely impossible to find.

Though the early Mazda sedans have a reputation for being stout and crashworthy, they are also subject to rust like any other Japanese car. Look in all the usual places that unit-body cars rust and remember that preformed parts and crash clips are the stuff of fantasy for the R100 restorer. The same is true for interior pieces and upholstery. Small parts will be very-very-hard to find. The old restorers advice to start with the best you can was never so true.