Renault is a secret to Red Bull’s recent success in formula one, the French carmaker claims.
The common perception, however, is that the energy drink-owned team has dominated the sport in recent years despite Mercedes-Benz actually supplying a more powerful 2.4 litre V8 engine to Red Bull’s rivals.

“The Mercedes engine is indeed about 15 horse power more powerful than ours,” confirmed Renault Sport F1′s Jean-Francois Caubet.

“But in terms of driveability and fuel economy, it is our engine in front. So when it comes to the bottom line, we are a little bit better than Mercedes,” he claimed to Germany’s Sport Bild magazine.

The most crucial factor, Caubet claimed, is the engine’s fuel economy amid the backdrop of the recent ban on in-race refuelling.

“Because our consumption is lower, Red Bull can start the races with 15 to 18 litres less petrol in the tank than the competition,” he said.

“That makes a big difference.”

Another factor is Sebastian Vettel’s driving, he agreed, with the back to back world champion having a “very fuel efficient” style, and being “extremely interested in the data”.

“They are both key factors when the driver wants to use the engine perfectly,” said Caubet.

Andre Lotterer on Friday boasted that his Formula Nippon single seater is faster than the F1 cars produced by F1 backmakers Virgin and HRT.

The 29-year-old German, who is leading the Japanese championship ahead of former Williams driver Kazuki Nakajima, won the series’ Suzuka round in May.

“Theoretically, if I would have entered today’s first free practice with my Formula Nippon, I would be nineteenth,” Lotterer, a Jaguar test driver in 2002, said at Suzuka.

In May, Suzuka pole sitter Naoki Yamamoto’s Honda-powered Nippon qualified with a time of 1.40.470, which was faster than any Virgin or HRT driver could manage on Friday morning at the same Japanese circuit.

And that Formula Nippon time is just half a second behind Friday morning’s slowest Team Lotus runner Karun Chandhok.

The 2011 Formula Nippon single seaters are built by American manufacturer Swift and powered by 3.4 litre V8 engines supplied by Toyota or Honda.

Christian Horner hopes Sebastian Vettel’s engine situation does not further dent his championship chances.

The Red Bull driver retired from the lead of the Korean grand prix last Sunday with a sudden and catastrophic failure of his Renault engine.

The 2.4 litre V8 unit that failed was the eighth he has used in races so far in 2010, but it had successfully completed 1600km of its projected life of 2000km.

But the other engines still available to the German are also quite high on mileage, which explains why Vettel did relatively few laps in practice last weekend.

“It’s obviously not an ideal situation,” team boss Horner said when asked about Vettel’s engine situation going forward.

“Hopefully it will have a negligible effect on him,” he added.

The price for customer teams of Mercedes’ 2011-specification KERS system has reportedly increased from an original EUR 1 million to 6 million.

Germany’s Auto Motor und Sport reports that F1 teams initially agreed that customer supplies of the energy-recovery technology next should cost purchasing teams just 1 million euros.

A further 5 million euros per team could then be spent on developing the systems.

But instead of receiving 1 million euro invoices from Mercedes, customer teams McLaren and Force India are reportedly being charged 6 million each.

The report, published on Wednesday, speculated that Force India in particular will not be able to afford the inflated price, in addition to its 9 million euro bill for Mercedes’ 2.4 litre V8 engines.

On the bright side for Mercedes’ KERS customers, the German marque believes it can supply a system next year weighing just 21 kilograms, compared to the 25kg system in 2009.

It is believed the other KERS manufacturers – Ferrari, Renault and Williams – are not going to follow Mercedes’ lead by increasing the price of their KERS systems.

Sam Michael, technical director at Williams, is surprised at the reports about high development costs.

“We have estimated the cost of our KERS at half a million pounds (sterling),” said the Australian, “and it will not weigh more than 25 kilograms.”