By Steve Keating
AUSTIN, Texas (Reuters) - Romain Grosjean was hailed as a future Lotus leader on Sunday after second place at the U.S. Grand Prix highlighted just how much progress the Frenchman has made since his 'first lap nutcase' days of 2012.
"You have represented Lotus in a very proud way," he was told by American great Mario Andretti, F1 world champion with the old Lotus team in 1978, in a podium interview.
"I guess number one in the team next year, right? Let's make it official."
Lotus have yet to announce their line-up for 2014, pending the promised arrival of new investors, but Grosjean is hitting a rich vein of form with six podiums so far this season.
Second place in Austin equaled the best result of his career and followed three third places in the last four races.
With 2007 world champion Kimi Raikkonen leaving the team at the end of the year, and absent from the last two races due to back surgery, Lotus have already made Grosjean the focus of their attention.
He repaid them with a storming drive after seizing second place at the start from Red Bull's Australian Mark Webber.
"A good result today, fantastic race," said Grosjean. "Being between the Red Bulls is a real achievement...it was probably one of my best drives of the year."
After a crash-filled start to his F1 career, and a rare one race ban last season for causing a first corner collision in Belgium, the Frenchman has begun to blossom at Lotus.
A furious Webber had labeled Grosjean a "first-lap nutcase" when they collided in Japan last year but has been far more complimentary this season.
The former GP2 champion has smoothed out the rough edges and developed into one of the circuit's promising young talents with increasing confidence.
"I never lost the self-confidence," said Grosjean. "If not, I would have collapsed a long time ago. I had a tough time but it was just a question of getting the right decision at the right time.
"Stepping up to Formula One is not an easy thing and you need time to get used to it. I maybe took a little bit longer than some other drivers but on the other hand I was still doing a very good performance."
With Finland's Heikki Kovalainen standing in for Raikkonen and drawing a blank on Sunday, Lotus needed Grosjean's haul of points in their battle with Ferrari for third place.
"Of course we are happy with his (Romain's) drive today and it's a great reward for the team," said Lotus team principal Eric Boullier.
"Actually, he pushed Mark to a couple of mistakes so it's good to see him driving like this today."
(Editing by Alan Baldwin)