Renault CEO Carlos Ghosn expects it to take three years before the returning Renault works team is competitive in Formula One.
Earlier this week, Renault finally confirmed it was going ahead with the takeover of the Lotus F1 team in order to return to the grid as a full works outfit. Lotus finished sixth in the championship standings this year with Mercedes engines, but Renault's V6 turbo power unit is currently off the pace of its rivals. Ghosn is expecting a tough few years to bring the the whole team back to the top of the sport.
"Given how keen our staff is, I think it will take three years to be competitive," he told French newspaper Le Figaro. "We'll also carry on developing our activity as an engine supplier, but only in accordance with the interests of our works team."
Renault has been deliberating over its decision to buy Lotus for most of the year and Ghosn said the company was faced with a choice of all or nothing.
"First of all, one should bear in mind that we decided to focus on our activity of engine supply in 2010, right after the global economic crisis. At that time, many other constructors simply left the sport, like Toyota, Honda, and BMW. We did not.
"However, over the past few months, we had to make a choice: either we came back as a works team or pulling out for good. Being an engine supplier does not yield a sufficient return on investments.
"We are deeply attached to Formula One, and I was also able to appreciate how a great number of F1 people - either from the FIA, FOM, or even our rivals - were attached to Renault. Our associates are also highly motivated to see us in F1. At Renault, there is a passion for racing."
Ghosn added that further details about Renault's F1 programme will not be released until January.
"You will have to wait for a few weeks. We will tell you about the organisation, the goals, the drivers, the strategy and the partners in January 2016."