LONDON, England - Not content with winning all four races so far in 2014, Mercedes team is heading to this weekend's (May 11 2014) Spanish Formula 1 GP intent on extending its advantage over the rest of the field.Lewis Hamilton and his Mercedes team mate Nico Rosberg dominated in Australia, Malaysia, Bahrain and China with Hamilton winning the last three in succession (Rosberg took Melbourne) but that - and the prospect of continued successes - is not enough for Mercedes whose motorsport boss Toto Wolff has called for a much greater effort in a bid to press home the team's advantage.As the F1 circus prepares for this the first 2014 race in Europe every team will arrive at the Catalunya circuit with upgraded cars carrying revised parts. Could this turn the start of the "European season" into a new beginning?'RELENTLESS RIVALS'Wolff said: "We know our rivals are going to be relentless in their effort to close the gap to us so our aim is to increase the advantage we enjoyed at the last race, in China. It is up to us to rise to the challenge, to take that relentless mentality to an even greater extent than those around us."If we are to build a sustained level of success in this sport then any small advantage must be seen as a platform on which to build a bigger advantage."Having seen how Red Bull's consummate superiority has been overturned, Wolff is fully aware of the frailty of any level of advantage in F1. He said he had long believed that Mercedes' advantage at the front of the field was not as great as some have suggested and warned that its dominance could come to a swift end unless it kept pushing."I believe this is an exceptional run and you cannot take it for granted," he said. "In a couple of years we will be looking back and saying that was really great - four races in a row and three doubles in a row - but we have to keep our feet on the ground and concentrate on developing the car further."We saw in China that our rivals were strong in some stints. We have to analyse that. We don't want to be caught on the back foot; the kind of spirit we are trying to maintain is that we do not have a comfortable lead but are fighting to stay on top."'STAY ON TOP'As Mercedes plans to stay on top so McLaren is battling to regain its competitiveness after a strong opening race in Australia was followed by a dip in form. Racing director Eric Boullier and chief executive Jonathan Neale have reviewed the team's operations and reacted with a raft of new signings - among them aerodynamicists Tony Salter from Sauber and Guillaume Cattelani from Lotus - ahead of the arrival in 2015 of a new 'aero' chief - Peter Prodromou.Boullier is convinced the changes will reap dividends. "McLaren is composed of brilliant individuals. They have won many races and have been fighting for championships. I think it is just to make sure that the same people are working together with strong leadership, strong guidance and, at least it will help them to recover their past success."The prospect of McLaren continuing to struggle in the doldrums 20 years after the death of Ayrton Senna shows the extent of the changes in the sport since 1994. Modern and safer circuits, quieter engines and a more corporate involvement are only three of the discernible differences in a sport that remains awash with money, fiercely competitive, technically progressive.Yet, the supremacy of Mercedes and the intra-team scrap between Hamilton and Rosberg have echoes of McLaren's experiences with Senna and Alain Prost in an age when the racing, the purest part of the sport, could rise and thrill audiences all over the world.Stay with Wheels24 for the 2014 F1 season – fresh reports every day.Can Merc wins its fifth consecutive GP and Hamilton his fourth at the 2014 Spanish GP on May 11? Email us your thoughts or use the readers comments below.