Fernando Alonso took a swipe at Honda after his drive to eighth in Brazil, saying Toro Rosso should be concerned by its 2018 engine partner's "amazing" lack of power at Interlagos.
Alonso spent much of the race in a battle with local hero Felipe Massa but, despite being quicker through most of the corners, struggled to get close enough to pass in the DRS zone. A lack of power has been a recurring theme for McLaren since it moved to Honda in 2015, but that partnership is coming to a premature end after the season finale in Abu Dhabi.
The Spaniard has often been Honda's most vocal critic and after the race he suggested Toro Rosso should take note of how its future engine partner performed.
"The lack of power today was amazing," Alonso said. "In Mexico the same. I was very, very close to Felipe a couple of times on the exit of the last corner, but even with the DRS he was pulling away. The lack of power is quite worrying for Toro Rosso next year."
Despite the power deficit, Alonso managed to finish ahead of rivals running Mercedes, Renault and Ferrari power units, something he sounded surprised about after the race.
"It's still a shame that we have this incredible power deficit and that with all the battery, the DRS and everything they are still quicker on the straight.
"Yesterday I think it was 25 km/h. Today when someone uses the DRS it must be 40 or 50, so it's pretty incredible that we finish in front of some cars. The lack of speed today was alarming. Only Abu Dhabi left and another complicated year ends. Hopefully it's the last race we have to race in these conditions."
McLaren will switch to Renault in 2018, the manufacturer Alonso won his two world titles with in 2005 and 2006.
"Renault has been the best engine company in the last 15 or 20 years, if you see all their titles, so we are confident for next year."