(Reuters) - Nico Rosberg vowed 'maximum attack' in a new title battle with Formula One world champion team mate Lewis Hamilton on Sunday as Mercedes unveiled their 2015 car before pre-season testing started in Jerez.
"I know the feeling of winning and of fighting for a championship after last year, but I also know the feeling of not winning in the end and I don't want to repeat that," said the German.
"It's an extra boost and it gives me so much motivation for the year ahead."
Rosberg, son of Finland's 1982 champion Keke, won five races last year to Hamilton's 11 and finished runner-up in a dominant season for his team and one that saw the drivers' relationship tested to the limit.
Mercedes are again expected to set the pace, even if the cars have not changed dramatically since last year's debut of the new V6 turbo hybrid power units and rivals hope to have closed the gap.
"It will be massively tough to repeat what we achieved in 2014 but we all want to keep that momentum going and to dominate the sport for many years to come," said Rosberg.
"We know the opposition will be right there, so we have to keep pushing flat out to have any chance of doing that. Nothing is for certain but, whatever happens, I know it will be another great battle with Lewis.
"This year is the rematch for me and I'm massively motivated for it."
Hamilton, now a double world champion after taking his first title with McLaren in 2008, agreed that there could be no complacency.
The Briton said he was also fired up for the season which starts in Australia on March 15.
"You hear about people who achieve a lot but then lose their focus and you wonder; at what point does it fade off? I'm grateful that the fire is still there in me," he said.
"I think subconsciously the taste of success spurs me on. I like that feeling and I want to feel it again and again," added the 30-year-old.
"I'm glad me and Nico had the battle we did last year. I love winning races but it just feels so much better when you have to fight for it. I just want to get back out there, race hard, be the best I can be and hopefully win some more."
(Reporting by Alan Baldwin in London, editing by Amlan Chakraborty)