Fernando Alonso said podium finishes would "probably not" be enough to satisfy him this year but he is realistic about McLaren's expectations.
The 35-year-old Spaniard said he was "100% committed to winning", adding: "I want to be world champion."
Alonso, champion in 2005 and 2006, has not won a race since 2013 as a result of a lack of performance from his cars.
He added that he had never considered joining Mercedes when Nico Rosberg retired at the end of last season.
In a news conference at McLaren's 2017 car launch, Alonso was in an expansive mood and discussed:
- his future, with his contract up for renewal at the end of 2017
- expectations for the season
- his motivation for his 16th year in F1
- his feelings about Rosberg's decision to retire
Alonso, a winner of 32 grand prix and one of the biggest stars in F1, also gave a withering response to his old rival Lewis Hamilton's recent observation that he regretted the amount of data-sharing in F1 because he felt it allowed his team-mates to learn from him.
Alonso said: "If he was watching more data from Rosberg last year, maybe he would have won the championship."
Alonso's expectations for 2017
McLaren have had two difficult seasons since the start of their engine partnership with Honda in 2015, with both chassis and engine less effective than those of world champions Mercedes.
Alonso said it was unrealistic to expect McLaren to close what was a 1.5-second gap at the end of last season in one winter.
"We need to recover a huge gap," he said. "Winning having come sixth in the previous constructors' championship is something no-one did apart from Brawn in 2009.
"We started 2017 early enough. We put a lot of resources in this year's car. We changed completely the philosophy of the engine, which is risky but needed if we want to win because the engine of the last two years was not good enough to win."
He added: "I expect Mercedes to still be very competitive. We saw their new car yesterday, which seems very well elaborated, and they have the advantage of the engine. They will be contenders. I am sure the Red Bull will be up there and hopefully we can put ourselves in that group."
McLaren have made it clear they wish Alonso to sign a new contract to keep him at the team after 2017, probably for at least another two years.
The driver reiterated his statements of last year that he hopes the new cars will see a return to "fighting spirit and racing spirit", allowing drivers to push hard at all times, before he commits. And he added that he was in no rush to make up his mind.
"After the summer break, around September, is a good time to start thinking and sitting with yourself and deciding what to do," Alonso said. "Until then, I will not think too much about the future.
"Obviously, I want to be world champion. That is what I am training for, why I was running and biking at -10C in the middle of the snow in the last month.
"Travelling to Australia (for the first race), normally I arrive on Monday or Tuesday, but this time I will arrive on the Friday before. I am 100% committed to win and if I can win this year it's better than next year."
On the Mercedes vacancy
Alonso was one of the drivers Mercedes considered as a replacement for Nico Rosberg, who announced his retirement five days after winning his first world title last November.
But the 35-year-old said he never seriously considered the possibility of moving.
"There were some phone calls that arrived to me but there was no point discussing anything because I was happy at McLaren," said Alonso.
"After the surprise of Rosberg they had to do a little check on everyone. It was nothing really strange or a deep conversation. It was a round-check they did with everyone - and me - to assess their situation.
"My situation was very clear. I had this year with McLaren and I am happy here. It was not a point to talk about any further."Alonso will be joined by Belgian rookie Stoffel Vandoorne for the 2017 Formula season.
On Rosberg's retirement
Alonso said he understood Rosberg's decision to retire at 31, but it was counter to his own nature.
"In my case, I cannot stop. It is like a drug," he said.
"For him he was very brave to stop. I wish him all the best. It was in his character. I am more a racer. I will be 80 years old in a go-kart pushing kids out of the track. Everyone is different."