Fabio Quartararo has emerged as Yamaha’s strongest performer during the latest Barcelona test, showcasing the first encouraging signs of the brand-new V4 MotoGP engine’s potential. The private test session at the Circuit de Barcelona‑Catalunya, held in early Aug 2025 (the most recent test available), featured Yamaha Factory Racing’s test riders Andrea Dovizioso and Augusto Fernández putting the new V4 prototype through its paces, while Quartararo monitored closely, primed for his own upcoming debut 

Though Quartararo himself did not ride the V4 at Barcelona, he topped overall times aboard Yamaha’s updated inline‑four M1 during the same week, confirming his status as the fastest factory rider under Yamaha’s banner. The event marked a milestone with the V4 being run on track publicly by Yamaha for the first time, and Quartararo’s role as the lead race rider places him at the centre of Yamaha’s next phase 

Yamaha’s unveiling of the V4 powerplant comes after more than a year of secret development. The rationale behind the switch lies in the performance gap to rivals – all of whom deploy V4 engines and have dominated since 2023. A report by the MotoGP organisation confirmed that the Barcelona test involved functionality assessments with Fernández and Dovizioso aboard the new unit, while also continuing development of the current inline‑four M1 concurrently 

Massimo Meregalli, Yamaha’s team boss, stressed that Barcelona’s work was exploratory, not performance‑based. He explained that the factory test riders were working to understand how the V4 behaves mechanically, and that Yamaha will only pursue it further when the bike’s performance merits that progression 

Quartararo is scheduled to be the first official factory rider to get a taste of the V4—with his debut expected during the official Misano test in mid‑September 2025. He confirmed as much at his appearance at the German Grand Prix in July, adding that until he rides the bike himself, all feedback remains speculative from the engineering team 

Technical insiders report that the V4 offers a gain of around two km/h in straight‑line speed and could deliver improved corner exit acceleration thanks to its compact crankshaft layout. However, preseason comparisons in unofficial testing at Brno found the V4 lapping approximately two seconds slower than the current inline prototype, though many laps were run under setup conditions rather than full speed runs 

For Quartararo, who topped unofficial times at Barcelona with the latest inline‑four M1 spec, the promise of the V4 offers hope of bridging Yamaha’s deficit on acceleration and top speed. At the same time, the transition poses adaptation challenges: neither Quartararo nor teammate Toprak Razgatlıoğlu have previously ridden a V4 machine, potentially making 2026 a “learning year” for both rider and team 
Yamaha technical director Massimo Bartolini, the driving force behind the switch, has emphasized that a full transition to the V4 will only occur if it proves definitively faster than the existing platform. This cautious but deliberate engineering direction underscores Yamaha’s urgency to close in on Ducati and Aprilia in an ever‑competitive field 

The upcoming Misano test in September will be critical. Quartararo’s feedback from riding the V4 will determine whether Yamaha pushes harder toward a new engine configuration or continues refining the tried‑and‑trusted inline design. Engineering sentiment within the paddock suggests Yamaha views 2026 as the season to race a V4 machine, with gaining in‑season experience likely to inform development under next‑generation MotoGP regulations 

In summary, the Barcelona test stands as the first public step in Yamaha’s pivot toward V4 architecture. With test riders completing functionality laps and Fabio Quartararo ready to lead the next phase, the V4 strategy is now firmly in motion. Whether it becomes Yamaha’s flagship MotoGP machine in 2026 hinges on upcoming data—but early signs suggest Yamaha might finally be steering toward a new era of competitiveness, driven by the fastest Yamaha rider at the moment.