Formula One will be just as exciting under proposals to make the sport greener and more relevant to the ordinary road user, according to BMW Sauber team boss Mario Theissen.

However he warned that cost control was crucial.

"There are many open questions and issues to be solved, but generally we think it's a positive move," Theissen said of discussions between the governing body and Formula One manufacturers about major technical changes from 2011.

"The ambition to pioneer road car-relevant technology through Formula One certainly will be beneficial to the role Formula One plays and the positioning of Formula One," he added in an interview with Reuters at the Monaco Grand Prix.

"As a technology frontrunner, BMW is happy about such a course.

"The difficult issue is certainly to keep costs under control and it will be important to make sure that really only road car- relevant technology will be put into the regulations in order to have this technology transfer and pioneering role.

"We need enough lead time to do the job with the resources currently available," added Theissen.

The International Automobile Federation (FIA) sent a discussion paper on power-train regulations to its Formula One Manufacturers' Advisory committee before the May 13 Spanish Grand Prix.

The committee, which meets next month, includes all the current F1 manufacturers -- Renault, BMW, DaimlerChrysler's Mercedes, Ferrari (FIAT), Honda and Toyota -- as well as non-participants Ford and the VW-Audi Group.

Theissen said the manufacturers had a sequence of meetings scheduled but it could take months before detailed discussions with the FIA.

ENVIRONMENTAL CONCERNS

The FIA has said the sport needs to cast off its gas-guzzling image and react to public concern about the environment.

The draft proposals include a switch to turbo-compounded 2.2 litre engines running on bio-fuel and producing around 770 horsepower.

They would also be rev-limited to 10,000 rpm and have to last for five races. That compares to the current 2.4 litre V8 units which are limited to 19,000 rpm and must last two races.

Theissen said the reduction in revs, half what cars were reaching two years ago, could be positive.

"I remember back in the turbo times, we had only a four cylinder engine, only 1.5 litres and only about 11,000 rpm but still more than 1,000 horsepower and it was so exciting," he said.

"So it's not just about engine speed. Maybe it will be about power again instead of revs."

DEEPER RUMBLE

The characteristic wail of a Formula One engine, so resonant in Monaco with the circuit hemmed in by buildings and the harbourside basin, is likely to change to a deeper rumble but noise levels will remain high.

Theissen said the use of biofuels was a challenge.

"Generally we support going in this direction," he said.

"But, again, it requires careful discussion because biofuel only makes sense if it's from regenerative resources and if these resources are available in a quantity which is relevant to road car fuelling as well."

Diesel technology, already used to power Audi to success in the Le Mans 24 Hour sportscar race, was not possible under current proposals.

"If we don't want to go below 10,000 rpm, then diesel is not an option," said Theissen.