Paul di Resta is being forced to consider a driving career outside Formula One as seats run out for next season.

Di Resta, 27, is coming to end of his third season with Force India and is 10th in the drivers' championship going into the final race of the season in Brazil this weekend. That is an improvement on his 13th and 14th places in 2011 and 2012 but he is still unsure of his drive for next season.

He is considering a number of options and might even follow his cousin, Dario Franchitti, into IndyCar.

"I built a good reputation in DTM [an international touring car racing series, which he won in 2010], and there are other opportunities in a few other series," Di Resta said. "I've always been slightly concerned about the safety of it [IndyCar], but sitting down and looking at it logically, it's a serious option to look elsewhere because of the success he has had."

Franchitti, 40, announced his retirement last week on medical grounds, following a horrific accident in Houston and Di Resta said at the time: "Racing in America is slightly different, isn't it? In Europe, [Franchitti] is probably under-appreciated. But to sit there at 40, having won four IndyCar titles and three Indy 500s – I would like to be in that position."

Force India, as usual, will not announce their 2014 drivers until the end of December but they want to re-sign the highly-rated Nico Hülkenberg from Sauber. The incumbent Adrian Sutil and Sergio Pérez, who has been dropped by McLaren, are favourites for the other seat.

Di Resta has not yet given up on his F1 career. "They know what I'm capable of here, they know what I can deliver. I feel like I'm an asset to the team," he said, "but I can't make the decision for them, and I have to respect their decision. I've said all along I'd love to be part of it.

"Things are getting tighter in the midfield to get seats, so I have to be content with what I've done, and I believe over the last four races I've done what's been asked of me. I don't know what will happen. I've got to wait and see. We're speaking, and that's all you can do. All is not confirmed yet."

Di Resta's manager Richard Goddard said recently: "There are a lot of drivers in the sport with money and a lot of teams that need money. That is probably the biggest issue, that it is not just outright talent that gets you a seat any more. Unfortunately, Paul doesn't have a government-backed scheme or a rich billionaire standing behind him."

Marussia are ready to re-sign the fourth British driver in F1, Max Chilton, even though he has been the last of the finishers on 11 occasions this season, and last but one on a further six.

But Marussia, who have already re-signed his team-mate Jules Bianchi, have been impressed by the popular Chilton's progress. Chilton is also the only driver among the smaller teams to finish every race.

Heikki Kovalainen, who has made a two-race comeback with Lotus, looks set for a full-time drive with Caterham next year.