This engine was capable of producing up to 224 kW (300 hp; 304 PS), thanks to the addition of a dual overhead cam design and four valves per cylinder.

During testing, it was discovered that rivets holding the 415S' monocoque structure together would start to loosen under lateral load, compromising the car's rigidity.

Testing continued through April, as Team Toyota carried out race simulations, and Yamaha purchased a Ford GT40 as a reference vehicle.

The added weight from testing also meant that the car was much heavier than the two-litre sports prototypes, including Taki Racing's Porsche 910 and 906, and the Nissan R380-IIIs.

Taki Racing's two-litre Porsches, led by runner-up Tetsu Ikuzawa in second, also finished ahead of Otsubo and Fushida.

Hosoya scored the 415S' first competition victory on 30 June at the All-Japan Suzuka Auto Racing Tournament, leading a sweep of the top four positions with Otsubo second, Mitsumasa Kanie third, and Fushida fourth.

Toyota entered five 415S, with newcomer Minoru Kawai (number 35) joining Japan Grand Prix drivers Fushida (#31), Fukuzawa (#32), Otsubo (#33), and Hosoya (#34).

[6] While Peter Revson's Shelby American McLaren M6B-Ford took the win after battling Mark Donohue's Sunoco Special McLaren-Chevrolet, Fukuzawa finished fourth as the highest-ranked Japanese driver, earning ¥1,152,000 from the prize purse.

Otsubo finished fifth, Hosoya sixth, Fushida eighth, and Kawai ninth, as all five Toyotas made it to the end of the race around Fuji's shorter 4.3 km course (run counter-clockwise).

[7] The project was overseen by Hosoya, and the replica vehicle was displayed at the Toyota Automotive Museum in Nagakute, Aichi Prefecture.

But due to problems with visibility and weight, Toyota discarded the closed-cockpit 474S in favour of a new open-cockpit body, shaped similar to a large broad wedge for increased front downforce.

Daihatsu Motor Corporation were now involved with the project, having lent their wind tunnel to Toyota and Yamaha to develop the redesigned open-cockpit body.

Two months after the open-cockpit body was completed, the revised 474S made its debut at the Fuji 1000 km, where the team of Fushida and Otsubo claimed Toyota's third consecutive victory in the event.

Former Daihatsu works driver Hiroyuki Kukidome joined Hosoya in car #2 (red), Fushida was partnered by newcomer Harukuni Takahashi in car #5 (dark blue), Kanie was partnered by Kiyoshi Misaki in the #6 (yellow), and Vic Elford was recruited to drive the #7 (green) entry, joined by Toshiaki Takahashi.

In addition, a modified McLaren M12 with the Toyota 79E engine was entered as a research and development car for Fushida, who retired after 21 laps.

Twelve 474S chassis were constructed, and the only survivor is Kawai's Japan Can-Am winning car, which was restored in 2007.The next evolution of the Toyota 7 was the turbocharged 578A.

The Toyota 7 Turbo was set to compete in the 1970 Japanese Grand Prix at Fuji Speedway, against Nissan's prospective challenger, the R383.

But on 8 June, Nissan announced that they would be withdrawing from the Japanese Grand Prix, citing their desire to concentrate on developing more efficient road vehicles in the wake of the 1968 Air Pollution Control Law.

Shortly thereafter, Toyota also announced they would withdraw from the Japanese Grand Prix, and the Japan Automobile Federation (JAF) cancelled the 1970 running of the race.

The turbochargers were removed from the V8 engine to bring the power down to 450 PS (330 kW) while the bodywork was a streamlined coupé design similar to other supercars of the era.

On 29 March 1968, Toyota survived a near catastrophe during testing for the upcoming Japan Grand Prix, when Yoshio Otsubo crashed through the guardrail at the 30° banked corner at Fuji, while driving the 3-litre 415S.

Minoru Kawai [ja] (9 December 1942 - 26 August 1970) joined Team Toyota for the 1968 World Challenge Fuji 200 Mile Race, and became a full-time factory driver for 1969.

Following Fukuzawa's accident, Kawai was given a more prominent role within Toyota as a leading driver and spokesman for the company, and his stature within the team grew following his win in the 1969 Fuji 200 Mile Race.