Convinced the Mercedes engine is fully legal, Williams boss, James Vowles empathises with "p****d off" rivals... sort of.

The Briton was speaking as testing got underway, just weeks before the opening race of the season, when the Silver Arrows and their customers could find themselves sidelined if the current engine row isn't resolved.

"My harsh line on it is the PU that we have in the car is completely compliant with the regulations," he told reporters in Bahrain. "It is not a month of work but several years of work to produce the PU to that level.

"We, as a sport, have to take care that this is not a BOP series," he continued. "This is a meritocracy where the best engineering outcome effectively gets rewarded as a result, not punished as a result.

"I'm sure other teams are pissed off," he admitted. "They weren't able to achieve what Mercedes did, but we also need to take care. Right now, I don't think there's a person in the pitlane that can tell you what is the best PU, and we only focus on one detail of it.

"My hope is that sense prevails and that we, as a sport, recognise that we are here to be a meritocracy, and that the best engineering solution wins as a result of it. Therefore we are where we are right now, but I maintain that our PU is completely compliant with all regulations.

"I've been with Mercedes for 23 years," he explained, "pretty much from the start of my career that's what I've always been a part of. The day I joined (Williams), I re-signed the Mercedes arrangement for pretty much that reason - which is that they are incredibly good at regulation changes, reading the rules exactly as the rules are, and making sure you push the boundaries of engineering. That is exactly what the PU represents right now for Mercedes."

Asked about the regulation at the heart of the row, he said: "First of all, they have to come up with a regulation - and good luck with them - where you're testing power units in the conditions you're trying to run on track. Anyone that knows anything about compression ratios, even if you've done your own cars, you kind of want to do it when it's ambient.

"I'm sure they can determine a way of testing it," he continued, "but the next element is that there are now two more steps. One: are we compliant even with any future regulation changes? No one knows that one particularly. And the second element of things is what do you do when you have effectively changed the rules? That now means that if we are not legal to it, that there are eight cars not participating on the grid. And that's what I meant by we, as a sport, have to really think about what the implication of this change is."

Despite many feeling that the sport's governing body has allowed the issue to drag on, the Briton admitted that the FIA has a hard task on its hands.

"To defend the FIA, the FIA has a hard job," he said. "You have teams filled with a thousand individuals thinking about how we can interpret the rules in a clever way.

"Let's be blunt about it, that's what teams do, and that's why we love the sport. It is difficult for the FIA. There's 20-odd people trying to fight against 10,000 out there on the grid. It's probably not that amount, but you get the idea behind it.

"The FIA do a really good job, generally speaking, of finding the boundary between clever interpretation and allowing it to go forward. What I'm stating here is that we need to take care that it's not just politically driven by other teams that didn't think of clever innovations now, and the FIA's job is to take a correct line of action on all of this."