Spain's two-time Formula One world champion Fernando Alonso warned today that it will be "difficult to stay awake" when driving on the country's highways under the new speed limit of 110 kilometres (68 miles) an hour.

The Spanish government said Friday it was lowering the speed limit on highways from 120 km/h as of March 7 as part of measures to reduce the country's fuel consumption in response to the rise in world oil prices due to unrest in the Middle East.

"I don't support this measure. To reduce fuel consumption there are other measures that are much more effective than this one. At 110 kilometres an hour, it is even difficult to stay awake," Alonso told reporters when asked what he thought of the measure.

Formula One cars race at speeds often in excess of just over 300 km/h.

Alonso, who won the Formula One title in 2005 and 2008, drives for Ferrari.

When Deputy Prime Minister Alfredo Perez Rubalcaba announced the new energy savings measures, he said a car running on gasoline will use 15 percent less fuel at the new, lower speed limit.

Alongside the lower speed limit, Spain will cut the price of commuter and short-distance rail tickets by 5.0 per cent and increase the proportion of bio-fuel used in diesel and gasoline from 5.8 per cent to 7.0 per cent.

Spain is almost completely dependent on imported fuel for road transport, although a fifth of its electricity output is generated by wind power, and the spike in oil prices has added to pressures on inflation and the trade deficit.

Each increase of 10 euros in the cost of a barrel of oil adds some six billion euros ($8.3 billion) to Spain's annual energy bill, according to government calculations.

During the 1970s oil crisis both the United States and Britain temporarily reduced the speed limit on highways in order to reduce fuel consumption.