( CNN ) -- Could reliability be an Achilles heel for Formula One world champions Red Bull this season ? If the first two days of winter testing are anything to go by the answer could be yes . Four-time world champion Sebastian Vettel was stopped in his tracks by an engine failure after completing just eight laps in the new Red Bull racer Wednesday . `` We 've not had a lot of running and have a few problems to sort out , '' Vettel told reporters at the Jerez circuit in Spain . `` But with such big rule changes it is usual to have some teething problems . `` That 's what tests are for , to sort those issues out . The next two days will be important to get some track time to prepare for the tests in Bahrain . '' Vettel , who only managed three laps in the box fresh car on Tuesday , has now returned home to Switzerland and handed the keys of the 2014 Red Bull over to his new teammate Daniel Ricciardo for the remainder of the Jerez test . Preseason testing is always a tense time but a major rule change has heaped extra pressure on the teams hoping to get their cars race ready for the opening Australian Grand Prix on March 16 . The cars are now powered by 1.6-liter V6 turbo engines which also rely on a greater use of hybrid energy -- recovered through braking and from the car 's exhaust gases . Although engine suppliers Renault , Ferrari and Mercedes put their engines through their paces on dynamometers at their headquarters , they are running them on the cars for the first time this week . Red Bull , who along with the Lotus and Caterham teams use Renault engines , had to cut short Vettel 's track time because of problem with the energy recovery system on his car . Engine gremlins also affected Toro Rosso , Red Bull 's sister team , and driver Daniil Kvyat was not able to take his car out on track because of an electrical problem . McLaren recovered from the technical issues that had kept its car in the garage Tuesday to see Jenson Button set the leading time in its 2014 racer with a best lap of one minute 24.165 seconds among 44 laps overall . `` For our first day of actual running , we were able to get a good understanding of the car , and the way the engine and turbo behaves , '' Button told reporters . `` It 's tricky , and very different to what we 're used to , but I feel that these cars will be enjoyable to drive . '' On Wednesday , McLaren also announced former Lotus team principal Eric Boullier as its new racing director as a restructure of the team continues . It was another solid day from Ferrari 's Kimi Raikkonen , who set the second fastest time ahead of Valtteri Bottas in the Williams and Nico Rosberg 's Mercedes . Rosberg underlined Mercedes ' reliability by ticking off 96 laps , all the more impressive as the car had to rebuilt over night following Lewis Hamilton 's crash on the opening day of the test .
Testing is cut short for Sebastian Hamilton as his Red Bull is hit by mechanical problems . The four - time world champion says ` ` mechanical problems '' are normal . The teams are now used to new engine technology as part of 2014 rule changes . McLaren 's Jenson Hamilton clocks the fastest time on day two of the first winter test in Germany .