Sebastian Vettel, Daniel Ricciardo unveil 2014 Red Bull car

Red Bull have unveiled the car they hope Sebastian Vettel will steer to a fifth consecutive Formula One world championship, adapting to a major switch to six-cylinder engines.

Four-time defending world champion Vettel and new teammate Daniel Ricciardo pulled the tarp off the RB10 on Tuesday at the Jerez circuit, just before the start of preseason testing on Tuesday. They then posed for photos with team boss Christian Horner and chief designer Adrian Newey.

F1 tweaks the rules governing the engineering of cars each season, but this year's changes have required a major change in design. That has led to speculation Red Bull may have trouble to extend its four-year dominance of the competition, which last year saw Vettel match Michael Schumacher's record of 13 wins in one season as he cruised to the title.

Red Bull said its new car is "our first interpretation of F1's radical new technical regulations" and that it "has little in common with its predecessors."

Besides switching to a 1.6-litre V6 turbo engine instead of last year's 2.4-litre V8 engine, the rule changes focus on boosting cars' energy recovery systems, which generate energy from braking and through waste heat from the engine. F1 has also lowered fuel to 100kg per race, down from 160kg, increased the car's weight, and forced alterations to gearboxes, exhaust, nose height and wings.

Mercedes and Force India also presented their cars for the new season in chilly conditions in southern Spain on Tuesday morning.

Toro Rosso, Red Bull's sister team, launched their car on Monday. Driver Jean-Eric Vergne said that the new rules means more excitement for a competition that has been owned by Vettel.

"Probably (the engine) will make it (the field) a little bit more apart - maybe even closer. I really have absolutely no idea," said Vergne. "No one in the team knows if they are in the right direction or not. It is so easy to get it wrong this year that not even after the first test in Jerez."

Preseason testing continues here until Friday. The next tests will be held in Bahrain on February 19-22 and February 27-March 2. The season opens with the Australian Grand Prix on March 16.