To give you an indication of just how quickly Yamaha taught itself how to build a GT car, the YX30 began testing in 1961, just six years before the Yamaha-built Toyota 2000GT was announced for sale.
Because the country was still under import restrictions in the late '50s, when the project began, Yamaha engineers began their sports car assignment after the kei-class was announced and quickly filled up with cheap, low-margin designs from Suzuki, Mitsubishi, Honda, and others. According to the always-excellent 2000gt.net, in late 1959 two Yamaha engineers were sent abroad to gather inspiration for a different market for the company to enter. Stops at notable manufacturers, including Porsche and Pininfarina, convinced the engineers that Yamaha could become, in some ways, Japan's low-volume carrozzeria for the production of sports, luxury, and GT cars.
With import restrictions in place, however—and no automotive manufacturing experience—the team was forced to use a competitor for inspiration, and were able to buy, drive, analyze, and dismantle a 1.6-litre, 4-cylinder MGA. And then (I love this part) the team did the same to a Facel Vega Facellia with a 1.6-litre, 4-cylinder engine, the very same motor that contributed a great deal to Facel Vega's demise.
While we'll never know if the engine in the YX30 was more MGA or Facellia, but the company came up with its first four-stroke motor as a result, an all-aluminum 4-cylinder at 1,580-cc of displacement. Output was a strong 88 horsepower at 5,600 rpm.
Now all the company needed was a car to test the motor with, so a fibreglass body was created to sit on a tubular steel frame chassis. The only problem? Japan didn't have race tracks or facilities to really test a car like the YX30 to its limit in 1961.
Using an unopened stretch of highway, however, engineers got a number that was good enough to lead to a second YX30, this time a 2+2 with steel bodywork—and a rear end design very similar to that Facellia. These prototypes led Yamaha to work with two competing manufacturers, Nissan and Toyota, until 1967 when the automotive division was focused on Toyota's 2000GT.
Oh, and that number? A top speed of 144 km/h (90 mph). Not bad for a 4-cylinder sports car in the late '50s. About 20 horsepower and 37 km/h (23 mph) down on a twin-cam MGA, but not bad…