The French constructor is currently considering several options concerning its involvement in Formula One and reportedly closing in on a return as a works team, with Enstone being the prime candidate for a takeover.
Although the Renault power unit stills trails its Mercedes counterpart, but also a much-improved Ferrari unit, Grosjean believes Viry can get its act together for 2016.
“It's always nice to be part of a constructor team and I'm sure Renault is going to improve its engine,” said the Frenchman, who started his F1 career racing for the manufacturer’s factory team in 2009.
“For sure now Mercedes is the best one on the grid, but next year is a long way away in Formula One.”
Lotus’ relationship with Renault stretches back to 1995 when the French engine supplier started providing V10s to the Enstone-based outfit, then known as Benetton.
It then became the Renault F1 Team in 2002 and went on securing two double world championships with Fernando Alonso in 2005 and 2006 before the French constructor started withdrawing from team ownership in 2010.
Renault remained an engine supplier to the replacing organisation, first named Lotus GP Renault then Lotus F1 team, until a 2014 torrid campaign, which ended with Enstone announcing it would use Mercedes power in 2015.
Click here for a lighter look at some scenes from the Hungarian Grand Prix