The season-opening Australian Grand Prix at Albert Park on Sunday week will be F1's greatest step into the unknown because of the sheer scale of the changes to the cars.

The biggest technical shake-up in 25 years - and arguably the most sweeping since F1 was codified in 1950 - has created an unprecedented scramble by the teams to be ready for the first race.

After just three four-day pre-season tests, some are better prepared than others, but none is certain how their cars will perform in race conditions.

The Australian GP will be the first true test and not even the best teams are confident of a trouble-free weekend, such has been the challenge of the new technical package.

Concerns remain about the reliability of the complicated new powerplants that, by F1 standards, are untried because of the strict limit on pre-season testing.

For the first time in more than a decade, a high attrition rate is expected at Albert Park - as well as subsequent early races - due to mechanical breakdowns.

F1 cars, and particularly their motors, have been so well developed and reliable that we've become used to most of the 22 cars reaching the chequered flag.

The root of all the uncertainty and angst is the most profound technical change - the switch from 2.4-litre normally aspirated V8 engines to turbocharged 1.6-litre V6s.

But the difference is much more than a smaller motor with forced induction.

While the V8s featured a rudimentary energy recovery system in recent years to provide limited boosts of electric assistance, the new V6s feature sophisticated systems to harvest waste energy.

On-board batteries store power produced by regenerative braking and heat from the turbocharger - which uses high-speed exhaust gases to spin a pump that feeds pressurised air into the motor's combustion chambers - to drive a pair of supplementary electric motors.

The turbo motors produce around 441kW (600 horsepower), with the electric motor generators providing a combined 80kW (160 bhp) burst of extra power several times a lap.

The new engines are so tightly integrated with the energy recovery systems (ERS) that F1 engineers now refer to the combination as a power unit. The total output means this year's cars will be about as powerful as last year's, but even the turbo engine alone will produce a lot more torque.

The V6s are limited to a maximum speed of 15,000 revs per minute, reduced from the V8s' limit of 18,000rpm.

Turbocharged engines dominated F1 in the 1980s until they were outlawed in 1989.

Unlike the previous generation, which were flame-spitting, smoke-belching, big-horsepower motors, the new generation are more about efficiency than outright oomph.

To give F1 a green tinge, the fuel capacity of the cars is limited to 100 kilograms (about 139 litres) - about a third less than last year - and fuel flow is restricted to 100 kilograms an hour when the engine is operating at more than 10,500rpm.

Drivers will be struggling to manage the savage power delivery while conserving fuel and also tyre wear, raising fears among F1 fans that there will be less at-the-limit racing.

The cars will be more difficult to control and drivers will have to resist the temptation to perform crowd-pleasing slides out of corners to save fuel and go easy on the latest iteration of Pirelli's purposely high-degradation rubber.

The move to turbocharged engines also means the end of the high-pitched wail that has been F1's sonic signature for so long.

The noise will still be loud, but not piercing, with the now-mandated single exhaust pipe emitting a throaty growl.

While the power unit is the major change, a raft of other new regulations have further complicated the design and development of this year's cars.

New limits to the front and rear wings, plus - most controversially - the height of the nose have resulted in a significant reduction in aerodynamic downforce.

As a result, the cars will be seconds slower than previously as the regulators wage their constant battle with F1 engineers to contain what would be ever-increasing lap speeds, which even the latest circuits could not contain if the spiral were not checked.

It has also produced cars that are, in the main, even uglier as designers have exploited the letter of the new rule limiting the height of the tip of the cars' noses to 185 millimetres.

Although introduced primarily to improve driver safety in front-to-rear and front-to-side crashes, the intent was also to replace the ungainly high snouts of recent years with more-elegant drooping shapes.

But for aerodynamic reasons, most teams have stuck with raised prows with awkward projections that comply with the maximum height requirement.

While certainly producing a greater variety of noses to distinguish the cars, most are unsightly appendages that have been compared with anteaters, echidnas, vacuum cleaners and, inevitably, an anatomical extension.

Other significant changes range from a standardised eight-speed transmission to further limits on how many engines and gearboxes can be used per car during the 19-race season.

Following the initial pre-season test at Jerez in southern Spain and two trials at Bahrain's Sakhir circuit last month, the Mercedes AMG team and others using Mercedes-Benz engines look to be in the best shape coming to Melbourne.

By contrast, Renault-powered teams struggled with the complex integration of software and hardware, with the world champion Red Bull Racing enduring a disastrous series of tests that left it with little real running ahead of Albert Park.

Mercedes' Lewis Hamilton and Nico Rosberg did the most testing kilometres with the fewest problems and generally set the pace, earning the most tenuous pre-season favouritism in years.

The pre-season tests were so problem-plagued that any form guide is highly qualified at best.

Force India, with McLaren reject Sergio Perez joining highly rated returnee Nico Hulkenberg, looked strong, while McLaren, with speedy newcomer Kevin Magnussen alongside wily veteran Jenson Button, appeared ready to rebound from last year's winless season.

Also a standout was Williams, which showed signs of finally emerging from its long decline. The team has been rejuvenated by the arrival of experienced technical staff and former Ferrari flunky Felipe Massa, plus a prescient change from Renault to Mercedes-Benz power.

Freed of his supporting role to first Michael Schumacher and then Fernando Alonso, Massa appears to be reborn in his new leadership role at Williams and was a regular front-runner in testing.

Ferrari was unconvincing despite Kimi Raikkonen rejoining the Italian team to form a top-heavy partnership with Fernando Alonso.

What is very clear, though, is that defending four-time world champion Sebastian Vettel and his new Australian teammate Daniel Ricciardo are unlikely to be dominant at Albert Park.

Their new Red Bull-Renault RB10 was so plagued with problems in testing that even Vettel doubts a dramatic improvement in time for Albert Park.

While millions of F1 followers will rejoice at the prospect of Vettel's reign coming to an end, the downside is that Ricciardo won't get a chance to shine as Mark Webber's replacement at RBR if the team's woes persist.

Foges' fearless five

Ahead of what’s shaping up as a turbulent F1 season, motor sport writer Mark ‘Foges’ Fogarty makes these bold predictions:

1) Fewer than half the field will still be running at the finish of the Melbourne GP. But by mid-season, new cars will be bulletproof and finishing rate will soar.

2) F1’s favourite anti-hero, Kimi Raikkonen, will not be happy back at Ferrari. Too much attention, too little performance and too much favouritism of Fernando Alonso.

3) Assuming Red Bull Racing recovers from pre-season testing debacle, Daniel Ricciardo will win races this season. ‘‘Smiling Assassin’’ will disarm Sebastian Vettel and charm the team with his sunny personality while taking no prisoners on the track.

4) F1 rookie Kevin Magnussen will upstage Jenson Button at McLaren, leading the team’s recovery. Smooth stylist Button will be stunned by Magnussen’s raw pace.

5) Melbourne GP will continue after 2015, most likely for another five years. Race will still cost the government the best part of $50 million a year, but Ron Walker will get a better deal from his mate Bernie Ecclestone that helps cap cost escalation. Maybe that last bit is wishful thinking…