By Andrew Benson
The 2006 Formula One season starts in Bahrain on Sunday with many observers predicting that it will be the most competitive in years.
With four teams appearing to have a realistic chance of winning races, we assess how each team is likely to fare this year.
Last season's worthy world champions start the new season as hot favourites for another helping of success.
Renault have shown impressive pace and reliability so far
The new R26 car has been consistently fast in pre-season testing and, despite F1's change to smaller V8 engines, it has also been ultra-reliable.
Fernando Alonso is leaving at the end of the season, but as engineering director Pat Symonds says, that is only likely to be a problem if the team are uncompetitive.
As that looks unlikely, the brilliant Spaniard is favourite to win a second consecutive title.
McLaren have made an impact with their new chrome livery, but shiny paint is not going to solve what looks like being their biggest problem.
McLaren look good despite a series of reliability problems
The team have already been afflicted by what has become a fundamental flaw in recent years - the reliability of the Mercedes engine.
Until mid-February, McLaren's winter testing programme was bedevilled by car failures.
But things improved dramatically after that, and in recent tests McLaren showed about the same pace as Renault.
With Fernando Alonso moving from Renault in 2007, Kimi Raikkonen and Juan Pablo Montoya know at least one of them will be out at the end of the season so both have plenty of motivation to do well.
Expect both to win races, but the title may again be out of reach.
Ferrari's pre-season form has been difficult to judge because they have rarely tested alongside their rivals.
Ferrari are tipped for a revival - but signs are mixed so far
Renault's engineering director Pat Symonds says he expects Ferrari to be "right back in the hunt", but the Italian team have appeared to be slower than Honda and Renault on the few times they have tested alongside them.
The signs are their car is better than last year's disappointing machine, but Michael Schumacher's chances are likely to depend on Bridgestone's tyres.
So far, the Japanese company appear to be lagging behind rival Michelin, which supplies Renault, McLaren and Honda.
But there will be races - and the San Marino Grand Prix, as usual, will probably be one - where Bridgestone have an advantage.
On those days, Ferrari could well dominate.
Toyota technical director Mike Gascoyne told this website last week that he believes the team "can be a match for Ferrari".
Toyota are bullish about their prospects of matching Ferrari
But few people outside Toyota share his optimism.
The team have done some strong lap times during the winter, but by common consent their longer-distance runs have not been as impressive and they have struggled with tyre wear.
Most expect the Japanese team to head division two behind Renault, McLaren, Honda and Ferrari.
Whether Gascoyne is right or not, Toyota's hopes of success - like Ferrari's - depend on tyre supplier Bridgestone.
There were a lot of people writing Williams off after engine supplier BMW dumped them last year to set up its own team.
Williams have looked solid but ininspiring so far
But Williams seem to have produced a decent car and the Cosworth customer engine appears to be reasonably competitive.
Nevertheless, while Mark Webber is one of the best drivers in F1 over a single lap, his chances of a win look slim.
Williams will probably be about where they were in 2005 - solid higher midfield runners.
Expectations are high after a series of impressive pre-season test performances - Honda have definitely won what cynical F1 insiders call the "winter world championship".
Honda look set to be major contenders in 2006
Renault's Pat Symonds says that Honda are where McLaren were this time last year - nip and tuck with Renault as the pre-season pace-setters.
But not everyone is so sure.
In their previous guise of BAR, this team have traditionally shown well in winter tests, and only once - two years ago - has this form translated into the championship proper.
Jenson Button and Rubens Barrichello make up an extremely strong driver line-up - second only to McLaren's in terms of combined strength.
But the team have yet to prove they have what it takes to win races.
Red Bull have made a big splash since making their F1 debut last year.
Red Bull's second F1 car has had a troubled first couple of months
Their impressive first season was followed by the biggest coup in F1 in years - persuading ace designer Adrian Newey to join from McLaren.
Newey, a genius, will undoubtedly make Red Bull winners in the long run, but he had no input into the design of this year's car, which has had a troubled early life.
Major overheating problems with the team's new Ferrari customer engine have seriously compromised preparations, and many insiders say they expect Red Bull to get a bit of a rude awakening in 2006.
BMW's decision to dump Williams last year and set up its own team was not popular in certain quarters of F1 and if the German giant struggles this year there will be a degree of schadenfreude up and down the pit lane.
Many expect BMW to struggle in their first season as a constructor
But the people running the team are no fools, and they gave themselves a solid base by taking over Sauber.
Expect a solid season with some good finishes lower down the points positions.
Midland always said that they should be judged on 2006 - not the season they had with an out-of-date Jordan last year.
Midland's first car has been reliable but slow in testing
So far, though, it appears that the first car produced by Russo-Canadian steel magnate Alex Shnaider's team will be no more competitive than the one they inherited in 2005.
It has been reliable but not much else in pre-season testing.
Red Bull's junior team has already been the centre of controversy.
Toro Rosso have attracted controversy with their car and engine
Firstly, they are running what is effectively last year's Red Bull, when F1's rules say teams have to build their own cars.
Secondly, they are the only team to be using a de-tuned V10 engine. This is allowed, but many teams say the amount of detuning has been incorrectly calculated, which will give Toro Rosso an advantage over many of the V8 engines run by other teams.
Coincidentally or not, they have done quite well in winter tests and look set to be well ahead of Midland, and perhaps even pushing Red Bull's main team.
Formula One's newest team will be an embarrassment to themselves and the sport for at least the first three races.
Super Aguri will be well off the pace for the first few races
Their late entry has left them running four-year-old Arrows cars at the start of the season and these are expected to be at least six seconds off the pace.
However, this is a team with a strong record in Japanese domestic racing and they are expected to eventually be sensible contenders.
How long that will take no-one knows.