McLaren driver Jenson Button said his car was not quick enough to compete at the Malaysian Grand Prix.
The Briton finished sixth in Malaysia - 36 seconds behind fifth-placed Nico Hulkenberg, driving for Force India.
Button's countryman Lewis Hamilton won the race, with Germany's Nico Rosberg second.
"I don't think the high speed here and the heat worked for us but there is no getting away from the fact that we are weak in high speed," Button said.
"We do have strength and that's why we are able to keep teams behind us but at speed we have got a lot of work to do.
"We finished 36 seconds behind Force India and they have been a bit of a surprise to us.
"We got the best out of today, and I am happy with that, but do have to improve to get close to the front rows."
Force India have picked up 29 points from the first two races, despite Sergio Perez failing to take his place on the grid in Malaysia after a software problem.
Hulkenberg, who rejoined the Silverstone-based team this season, took sixth place in the season's opening race in Australia and was fifth in Malaysia, one place behind Ferrari's Fernando Alonso.
He said: "After the start, I was in a nice comfortable position so it was easier to manage the tyres and fuel which was good.
"Alonso was eating me alive but I knew there was no way to keep him at bay. I was expecting McLaren - and more so Williams - would be all over me but we performed very well."
Marcus Ericsson, who spun off in qualifying on Saturday and retired in Australia, finally completed his first race for Caterham.
"I want to thank the boys in the garage for working so hard to fix my car after yesterday's accident," he said.
"I was feeling a bit low last night, but to have finished my first full Grand Prix in 14th, helping us move up into 10th place in the constructors' championship, is a great feeling, for me and everyone in Caterham."
After finishing second in his F1 debut in Australia, McLaren's Kevin Magnussen finished ninth in Malaysia and was involved in controversy - earning a five-second stop-go penalty after a collision with Kimi Raikkonen's Ferrari on the second lap.
The incident caused Raikkonen a puncture and dropped the Finn to the back of the field, although he recovered to finish 12th.
Magnussen said: "I'm sorry for the team that I messed things up going into the second corner, with the incident with Kimi. I think we could have scored some good points today, so I'm disappointed with and for myself, too. They are long races, so I shouldn't have made a mistake like that so early on in the afternoon.
"But that sort of stuff happens sometimes - and, when it does, you just have to learn from it, and I will."
It was also a day to forget for Red Bull's Daniel Ricciardo, forced to retire after 49 laps and handed a 10-place grid penalty after the race for an unsafe release from the pits, which will affect his starting position on the grid in Bahrain next week.
The Australian was disqualified from his home grand prix two weeks ago for a breach of fuel rules.
Ricciardo said: "I'm really disappointed, but at the same time there's a little bit in me which is happy because I think I've come out of the first two races how I wanted to.
"We've started off on the right foot, so for that I'm pleased and with a little bit of luck we'll turn things around soon and I'll get some points. I love racing up the front, it's been a privilege and a lot of fun in the last couple of races."