By Andrew Benson Motorsport editor

Will the smiles last now Raikkonen and Montoya are team-mates?

Formula One will wave goodbye to 2004 without regret.

For all but the most partisan Ferrari fan, there was not much to get excited about on the track, and bitter politics off it made the atmosphere around the sport poisonous.

But a new year brings hope of a fresh start - and there are plenty of intriguing unknowns about the 2005 season.

F1's pre-season is traditionally characterised by blind optimism on behalf of all the teams and drivers - and none more than those who are in new partnerships.

Usually these dreams are quickly broken by the harsh realities of a sport in which there is no easy route to success.

McLaren could be driven to new heights with Montoya's arrival

This time, though, a couple of the new combinations have a buzz of genuine excitement about them.

Chief among these is Juan Pablo Montoya's move to McLaren as team-mate to Kimi Raikkonen.

F1's two most exciting young talents are now together in the team that, on balance, has provided the most consistent opposition to Ferrari in the last seven years.

Raikkonen and Montoya ran Michael Schumacher close for the title in 2003 when the Colombian was still at Williams - and one senses they are the only two men who Schumacher genuinely worries about, with the possible exception of Renault's Fernando Alonso.

And many F1 observers - not least McLaren boss Ron Dennis - are licking their lips about the potential for their partnership.

On one level, it will be fascinating to see how they compare regardless of whether McLaren can challenge Ferrari.

The potential for fireworks at McLaren is massive

Neither man is under any illusions about how important it is to come out on top.

At stake is the unofficial title of second best driver in the world - a status that will be upgraded by one after Schumacher's anticipated retirement in 2006 - as well as being the main focus of one of the sport's greatest teams.

At the same time, this personal battle is likely to drive McLaren's performance ever higher as each man pushes to the limit in his desire to beat the other.

It will not be an easy time for either driver, or McLaren as a team. But the potential for fireworks - on and off the track - is massive.

McLaren are not the only team to have refreshed their line-up in the quest for improved performance.

Webber seems to have found his spiritual home with Williams

Mark Webber's move to Williams is also laced with spice, and the early feeling is that team and driver have found their perfect match.

Williams are renowned for their no-nonsense, down-to-earth, straightforward approach, and Webber - as archetypal an Australian sportsman as you will find - fits perfectly into that mould.

Williams will need to improve what has become a patchy record in producing competitive cars.

But the impression is that Webber is just the man to help a formerly great team rekindle memories of its success with another Australian, the 1980 world champion Alan Jones.

At Renault, the return of the stylish, quick and experienced Giancarlo Fisichella sets up an intriguing battle with Alonso.

And at Toyota, F1's not-yet-awoken giant, there is a new sense of purpose.

The excuses are running out for Toyota's F1 team

The Japanese car company's F1 team have made little impression so far, but 2005 is the year in which the sport will get a sense of what they might be able to achieve.

Signing two proven winners in Ralf Schumacher and Jarno Trulli puts the team firmly in the spotlight, in that any lack of performance will clearly be in the car.

And this season will see the first new car fully designed under highly-rated technical director Mike Gascoyne, who was poached from Renault a little over a year ago.

On a reputed salary of $6.5m (�4m), Gascoyne is under serious pressure to deliver.

The new cars wheeled out by the F1 teams in the coming weeks may well look similar to those that did battle in 2004, but they will be hiding a raft of changes.

They have been designed to new rules aimed at reducing costs, slowing the cars and - hopefully - improving the racing.

The most dramatic changes are restrictions to the aerodynamics and tyres, aimed at reducing cornering performance by as much as 25%.

F1 to make rule changes

Added to the requirement for tyres to last an entire race, that should mean the cars' cornering speeds will be cut significantly.

F1 bosses also hope that a restriction of aerodynamics might make it easier for drivers to follow closely through a corner, thereby assisting overtaking.

Included in the package of rule changes is a requirement for engines to last two entire race weekends.

But while this will have a dramatic effect on costs - and make customer engines for smaller teams cheaper - it will have little outward effect as far as the spectator is concerned.

The inter-team antagonism that marked 2004 shows little sign of abating, and the row over the financial future of the sport lumbers on.

The teams are split into two opposing camps - with Ferrari isolated in opposing major changes aimed at dramatically reducing costs - and there is little sign that a compromise can be reached.

Meanwhile, the threat of a breakaway series by Ferrari, Renault, BMW and Mercedes in 2008 still hangs over F1, and there appears to be no looming accord in that row either.