Karthikeyan drives for Spanish outfit Hispania Racing Team and Hamilton said a driver can not do much in a slow car.
"It is unfortunate that Narain is driving a slow car. Other drivers would also struggle in slow car and it does not mean you are a bad driver. It would be wonderful if he were in Force India which is a pretty good team. It would be a huge stepping stone for him," Hamilton said here.
Hamilton said it helps when one drives for a country's team.
"I am a Brit, driving for a British team in a British car. To me it's very positive and it has done wonders for us so I hope it would be the same for him and India," he said.
A 15th place finish at the Monaco Grand Prix is Karthikeyan's best result this season.
One seat will left in Force India for the 2013 season as Nico Hukenberg is expected to leave the side for Sauber.
However, Karthikeyan has indicated that he would stay at the HRT for the next season.
