Motoyama was suspended for the final round of that year's Formula Nippon championship and the JGTC All-Star Race at Twin Ring Motegi, and fined ¥500,000.
Motoyama made his debut in the All-Japan GT Championship in the third round of the 1996 season at Sendai Hi-Land Raceway, driving a GT300 class Nissan Silvia S14 owned by Kazuyoshi Hoshino.
For the 1997 season, Motoyama stepped up to the premier GT500 class, driving alongside Hoshino in the Calsonic Nissan Skyline GT-R for Team Impul.
Motoyama only missed the second round of the 1999 season at Fuji Speedway, as he was participating in a pre-qualifying session for the 24 Hours of Le Mans that same day.
Despite not winning a race, Motoyama and Krumm's consistency in the #23 Xanavi Skyline GT-R was enough for them to become GT500 champions, clinching the championship with a third-place finish at Suzuka.
In 2010, Motoyama and Tréluyer failed to win a race for the first time, coming as close as two second-place finishes at Sepang, and at the Suzuka Summer Special in August.
In the final year of Motoyama and Tréluyer's partnership at Nismo, they won three races, at Fuji, Autopolis, and Motegi, and finished runner-up in the GT500 championship.
After switching from Nismo to two-time reigning GT500 champions MOLA in 2013, Motoyama claimed his last victory in the 2015 Buriram Super GT Race held at Chang International Circuit.
Reigning Blancpain GT Series Endurance Cup champion Katsumasa Chiyo joined Motoyama at MOLA for the 2016 season, and the duo scored a podium finish on debut at Okayama, and another podium finish that year in the Suzuka 1000 km, with Mitsunori Takaboshi replacing an injured Chiyo.
Motoyama finished a distant third in the championship behind Toranosuke Takagi, taking one win, two poles, and four podiums in the final four races.
The 2001 season started with Motoyama taking three pole positions through the first four rounds, and a victory at Miné, but two retirements and a non-scoring finish saw him trail championship leader Naoki Hattori by 22 points after four races.
However, Motoyama took victories in three of the following four rounds, taking the championship lead as Hattori began to struggle, and eventually clinching his second Formula Nippon title with a second-place finish at Motegi.
Motoyama was unable to celebrate his win at Fuji, however, after he learned of his childhood friend Daijiro Kato suffering critical injuries in a crash during the 2003 MotoGP World Championship round at Suzuka.
In December 2020, Motoyama returned to single-seater racing, competing in the final round of the Formula Regional Japanese Championship at Autopolis in a car entered by Team Goh Motorsports.
The team fielded an Audi R8 LMS GT3 Evo for himself and former All-Japan Formula 3 National Class Champion, Yoshiaki Katayama.
[8] Motoyama has competed at the 24 Hours of Le Mans four times, making his debut in 1998 with NISMO and Tom Walkinshaw Racing in one of four factory Nissan R390 GT1s.
Motoyama and co-drivers Érik Comas and Michael Krumm ran as high as fourth place overall in the #22 R391, before retiring after 110 laps with an electrical issue.
After thirteen years away from Le Mans, Motoyama made his return in 2012, driving the Nissan-powered DeltaWing experimental prototype for Highcroft Racing alongside Krumm and Marino Franchitti.
In one of the race's most memorable moments, Motoyama spent two hours trying to repair the DeltaWing, as his Nissan mechanics stood behind the spectator fencing to give instructions.
On October 10, 2003, Motoyama was given a Friday test drive for the Jordan F1 Team prior to the Japanese Grand Prix at Suzuka Circuit.
He ran the 2019 Fuji 24 Hours, driving a customer Nissan GT-R NISMO GT3 for Tairoku Racing with B-Max Engineering, and finished 2nd overall.
Motoyama was expected to return to the team for the 2020 Super Taikyu Series, but their entry was suspended due to complications caused by the COVID-19 pandemic.
Two years prior, he competed as the owner and driver of SKT Team Motoyama, fielding a Nissan Fairlady Z34 in the ST-3 class.