Lewis Hamilton will be strong as long as he's motivated, says Jolyon Palmer

Hamilton won back-to-back drivers' titles in 2014 and 2015

Three-time world champion Lewis Hamilton's desire to win more titles could depend on his life outside of Formula 1, says Renault driver and fellow Englishman Jolyon Palmer.

Hamilton, 31, missed out on a fourth drivers' title this year to now-retired Mercedes team-mate Nico Rosberg.

Palmer says Hamilton is in a "good place" for next season, but does not know how long he will stay at the top.

"So long as he's motivated, he'll be strong," Palmer, 25, told BBC Sport.

"He enjoys more of life outside Formula 1 than a lot of other drivers.

"At the moment, he is very competitive with it and is able to combine Formula 1 with quite an elaborate lifestyle outside of the car.

"But you still need the right circumstances. You need a good team behind you and you need to have a reliable car for the year to do it - it's not just up to him."

Rosberg retirement a 'shock to F1'

Rosberg won his first World Championship in 2016 - then retired

Hamilton is yet to learn who he will drive alongside next year, with Rosberg, 31, having retired five days after winning the title.

The German said the time was right after achieving his "dream", but Palmer says it came as a "massive shock" to everyone inside the sport.

"I couldn't really believe it," he said. "It's the best job. To be champion, to be in the best car and being paid a huge amount of money.

"It is what everyone else is aspiring to do, so to be in that position and call it quits is difficult to understand for a lot of other people.

"I would love to be in that position, but I don't have a family and kids. I respect him, because from that position it is a very brave call."

Palmer, who will drive alongside Nico Hulkenberg next year, believes Hamilton will have an "advantage" over whoever Mercedes recruit to replace Rosberg.

"Anyone else is going to be coming in new to the team, and also pretty late without the preparation that most others have had," he said.

Palmer says it will be tough for Mercedes to replace the world champion because the "main contenders" are all under contract.

But he added: "I don't doubt they will be fine. They still have Lewis Hamilton in the car and whoever they do get in the second car will be a very capable driver anyway.

"It is harder for them, and I'm sure they would much prefer Nico was staying on, but I think they have been so dominant the last few years they should be able to transfer that in to the next generation of cars and at least be race winning."

Michael Schumacher won five successive titles with Ferrari, following two with Benetton

Can Hamilton break Schumacher's record?

Palmer believes Hamilton is the fastest driver in Formula 1, but says his compatriot has a tough task to emulate Michael Schumacher's seven World Championship wins.

"The Red Bull guys are coming stronger and stronger," he said.

"If you look at Fernando Alonso, he was the youngest ever champion and won two in a row. No-one would have been thinking 10 years on he would still have only won two championships.

"Even though, at a certain time, you can be the best driver in the best car, it doesn't mean you can keep on winning those championships."

'No need to panic for British motorsport'

Palmer and Hamilton are set to be the only two British drivers on the grid in 2017

Palmer made his F1 debut for Renault last season but, following Jenson Button's retirement, he and Hamilton look likely to be the only Britons on the grid for the start of the 2017 season.

Having finished 18th in the standings this year, Horsham-born Palmer expects a "much better year" in 2017, and says there is "no need to panic about the British drivers".

"There have always been a lot of good Brits that have been knocking on the door of F1," he added. "We've still got two, which is a reasonable amount, especially when one is in a championship-winning position.

"I'm sure we will be well represented in GP2, GP3, Formula 3 and it will be a matter of time before someone else comes in.

"There is such a heritage of British drivers and eight out of 11 teams are based in the UK, a lot of junior teams as well. So I think British motorsport is still in a good place."