A collection of leading automotive manufacturers have warned that the new emissions rules being implemented in California could prove ruinous for the industry.

The Alliance of Automobile Manufacturers (AAM) says that the California Air Resources Board's (CARB) emissions reduction rules come at a time when incentives are being widely used in order to prop up a flagging industry.

Under the new regulations, exhausts from cars and light trucks must be reduced by 25 per cent, with bigger trucks and SUVs required to slash emissions by 18 per cent.

A target date of 2009 has been set for the introduction of cleaner automotive technology, with all vehicles expected to meet the new air standards by 2016.

With the proposals still awaiting approval by the California state legislature, AAM spokeswoman Gloria Berquist is keen to underline the potential difficulties the organisation has identified.

"They are proposing that we build vehicles that don't exist today using a combination of technology . . . It's a theoretical vehicle," she commented.

The AMM says that “even zero-emission hydrogen vehicles could not meet ARB's proposed standard in 2016”.

Indeed, it expects that the required technological upgrades would cost the average Californian driver an extra $3,000 on new vehicles.

The organisation represents Ford, General Motors, DaimlerChrysler, and Toyota among others.