Chris Evans quits Top Gear after one series
TV and radio presenter Chris Evans has quit Top Gear after just one series.
Evans joined the motoring show last June following the departures of Jeremy Clarkson, James May and Richard Hammond.
The 50-year-old said Top Gear was his "favourite programme of all time" and promised to "take it forward".
But despite positive reviews, the show struggled to match the ratings of the Clarkson era, attracting fewer than two million viewers for the series finale on Sunday.
Evans tweeted that he "gave it my best shot but sometimes that's not enough."
The presenter said he remained committed to his other BBC shows, including Children In Need and Radio 2.
In a statement, he said his resignation was "the single best thing I can now do to help the cause".
"I have never worked with a more committed and driven team than the team I have worked with over the last 12 months," he said. "I feel like my standing aside is the single best thing I can now do to help the cause.
"I remain a huge fan of the show, always have been, always will be. I will continue to focus on my radio show and the allied events that it encompasses."
Evans' stint on the show has also been plagued by speculation that his relationship with co-presenter Matt LeBlanc had broken down.
LeBlanc had threatened to quit if Evans continued in the role, newspaper reports last week suggested.
Mark Linsey, director of BBC Studio's, said: "Chris is stepping down from his duties on Top Gear. He says he gave it his best shot doing everything he could to make the show a success.
"He firmly believes that the right people remain, on both the production team and presenting team, to take the show forward and make it the hit we want it to be."
Perry McCarthy, the original Stig in the first two series of Top Gear, said he "wasn't surprised" that Chris Evans had stepped down, adding that the presenter was "normally a genius" with everything he tried, and that not getting something quite right must have been hard for him.
McCarthy said that he thought the issue with the new version of the hit-show was that the first episode "wasn't very good", but that it had picked up since then.
Questioned on the rumours of rivalry between Evans and LeBlanc, McCarthy said he did "wonder if some of it is true", but added that a "very big name" would be needed to replace Jeremy Clarkson and Evans.
Former co-presenter of Top Gear Tiff Needell thinks the BBC "need to step back a bit, adding "they tried to run before they could walk".
"They've gotta take the pressure off the show, it doesn't have to sell around the world in such great numbers, the former racing driver told ITV News.
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Giving his thoughts on how the motoring show could be improved, he said: "It just needs a bit of format tweaking, maybe less presenters, concentrate on ones that have some chemistry going.
"Matt Le Blanc, I think, surprised a lot of people, but how long is he going to want to do Top Gear for, that's a concern I would have thought," he added