Honda's progress in Formula 1 will be slowed by the increased need for reliability that will be demanded now it has teamed up with Red Bull, reckons Renault.
Although Red Bull hopes that Honda can continue the rate of progress it showed with Toro Rosso in 2018, Cyril Abiteboul - F1 managing director at Red Bull's former engine partner Renault - is sceptical.
He thinks Honda's improvement last year was flattered by its policy of introducing regular engine upgrades regardless of the grid penalty implications.
Over the course of the season, Toro Rosso's Brendon Hartley and Pierre Gasly both used eight internal combustion engines, turbochargers and MGU-Hs - twice as many as any other driver. The rules allow only three power units before grid penalties are applied.
Abiteboul believes Honda's improvements will be pegged back once it has to stick to the three-engine limit like the other manufacturers.
"Yes they can spend as much as they want at the factory and they decided to introduce as many engines as they want last year, but that will be naturally regulated if they have to take engine penalties four or five times this year," Abiteboul told Autosport.
"No one is making any noise when that happens to Toro Rosso, but I expect a bit more noise if that has to happen to Red Bull. So that will naturally slow them down.
"If they want to comply with the regulations, they will have two or three shots maximum to improve their power unit during the season. Just like it happened with us last year."
Renault made a C-spec version of its 2018 engine available to its customer teams after the summer break last year, but only Red Bull chose to use it.
While it provided an increase in performance, there were concerns about its reliability.
McLaren and the works Renault team therefore stuck with the B-spec until the end of the campaign.
Abiteboul added: "It could have meant more progress, and we had even ourselves the same opportunity as Honda.
"But we were also in a constructors' championship, and we knew taking grid penalties would have a severe impact on our ability to score points and therefore secure our position in the championship. That is something we did not want to do.
"Honda is a threat in a sense, but they are a threat like everyone else.
"I expect that threat will be slowed down in its progress and I have confidence in the gains we have made this winter."