Red Bull master designer Adrian Newey has mocked Formula One's new engine rules, claiming they have produced slower cars without achieving the intended green goals.

Speaking ahead of Sunday's Bahrain Grand Prix, Newey - who designed the cars that won Red Bull the past four drivers' championships - said the new 1.6 liter V6 turbo hybrid engines have increased costs and slowed down the cars for little benefit.

He said the environmental aims of the hybrid engine could have been more efficiently met by reducing the cars' weight without compromising speed, and that there were more ways to be relevant to commercial car production than fuel efficiency alone.

"The cost has gone up hugely to create this," Newey said. "If you put that cost into weight saving, you might be better off in many cases, so to automatically say that this is some huge benefit for mankind is taking a bit of a big leap. There is a relationship between cost, weight, aerodynamics . all sorts of factors, if you're going to go into road relevance. How you weigh that, how you proportion it, is impossible for an open-wheeled single-seater. It's a very different beast."

The new engines have been criticized both for creating a muted sound, and also for producing a processional style of racing as cars circulate in fuel saving mode to stay under the 100 kilogram per race limit.

"Formula One should be about excitement," Newey said. "It should be about man and machine performing at its maximum every single lap. OK, they're using 50 kilos less fuel (per race) but they're going a lot slower to achieve that."

However, rival engineers disagreed with Newey, saying the sport had risked becoming too far removed from normal commercial engines and that the technological innovation should be celebrated rather than criticized.

"There was a great danger ... that we would become irrelevant, we would become the focus of gas-guzzling and not having social responsibility," Williams technical chief Pat Symonds said. "It was really important that we did move away from that."

Paddy Lowe, the technical chief of Mercedes which has dominated the early stages of the season, was surprised by criticism of the changes.

"I don't understand it because there are so many positives around this formula," Lowe said. "For an engine to deliver similar power to last year, with more than 30 percent less fuel consumption, is just an incredible achievement and it's something we should celebrate. Our fans like that richness in the sport.

So I hope they also appreciate what's been done on the cars and its sort of relevance to the future in the automotive industry generally."

Bob Fernley, the deputy chief of Force India, said the efforts to make the engines more relevant to road-car production have already borne fruit.

"Honda are coming in next year and it's the first time we've had another major motor manufacturer coming back into Formula One for a long, long time, so that's a tick in the box that says that actually Formula One has got it right," Fernley said.

"We're going to find that the fans are going to embrace this as we go on in the years to come."