Romain Grosjean admits it has been a "good start to the season" for Lotus, adding that the team's improvement is mainly due to the E23 chassis.
The Enstone squad endured a nightmare 2014 campaign as problems with the Renault engine and E22 chassis saw them finish eighth in the Constructors' Championship with just 10 points.
They appear to have turned things around this season as Grosjean has already picked up 16 points after five races.
Asked by Sky Sports Digital to rate his personal performances so far, he replied: "Pretty good to be fair. It’s always hard to rate yourself, even though I’m ‘R8’! [Romain’s initial and car number]. Qualifying-wise there are always laps you could have done better and so on, but race-wise I think we have achieved 100 percent of what we could.
"There are always times when you can think ‘oh, I could have done that a little bit better’ but in general I’m pretty happy with the way I’ve been driving, the way my engineers have been working with me – especially as we changed a little bit the structure of the team – and the way the team have been reacting to problems or performance.
"To be fair, it’s a good start to the season."
After their troubles with the Renault engines in 2014, Lotus switched to Mercedes power units this campaign and many believe it is one of the major reasons for their return to form.
Grosjean, though, believes a lot of credit has to go to those who have worked on the E23 chassis.
"To me, it’s mainly the chassis. The engine is a straight line – if you are 310 or 320 [kph] in a straight line you won’t see the difference," he said. "Of course, the Mercedes is a world champion engine and everything was ready, it was just ‘plug in and go’, rather than last year where we had new technology coming into Formula 1 and everything had to be set up. So it was a big difference.
"To me it’s when you turn right, this year’s car turns right! Last year that was not the case. It seems a bit crazy to say so, but it’s the best example I can give."