It may still take a while before a clearer picture on this year's pecking order emerges, according to Red Bull team boss Christian Horner.
Unlike previous seasons when the Spanish GP was a true barometer of the strength of all the teams, this year's race at the tricky Circuit de Catalunya may not reflect the true potential of all the teams due to the competitiveness of the field.
"Usually Barcelona is a pretty good indicator of car performance: if a car works well there it tends to work well in most places," Horner told Autosport. "Whether that still applies this year, who knows?
"I'm sure most teams are bringing upgrades of varying degree for that Barcelona race. It is the first European race so traditionally that's where teams will introduce new components to their cars and we're no different to that. It will be fascinating to see the evolution amongst the teams."
It is anyone's guess who will win in Spain as the first four flyaway races have delivered four different winners from four different teams.
Horner admits it is difficult to predict how the rest of the season will pan out.
"McLaren came out the blocks very strongly, and certainly the first couple of races they looked very, very competitive, but then suddenly Mercedes turned up in China, and Lotus was strong in Bahrain," he said. "It's moving around a lot.
"Historically McLaren and Ferrari have always been very strong, but the competition is broader this year. Mercedes and Lotus have been strong, plus Sauber came perilously close in Malaysia, and I don't think many would have predicted that."
He added: "It's exciting. I think the races have been very good this year. For us we'd like a boring, dominant Championship but from a sporting perspective it's great to have competition, and it is great for there to be so many cars and drivers capable of turning up at a grand prix and capable of winning."
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