Fifty or 60 years ago frugal motorists emerging from wartime rationing would turn off their engines at every opportunity to save petrol. Now a new range of fuel-efficient vehicles will do it for them, stopping the engine every time the car stops, as Australia, like the rest of the world, heads towards a future of ever increasing petrol prices. There's also hybrid models, running on a combination of petrol and electric power, super efficient diesels, small turbo-charged models and mini petrol-driven cars designed to sip rather than guzzle. Conversion kits to run cars on liquefied petroleum gas (LPG) are running hot with the industry now designing versions suitable for four-cylinder cars. In the future there will even be cars running on compressed natural gas (CNG) and plug-in electric models. While hydrogen power and fuel cell cars are still under development. It's all part of the brave new world of motoring as oil prices continue to rise pushing up the price of fuel and with it just about everything else as transport costs soar. Just this week petrol in most states crashed through the $1.60 a litre barrier with some predictions it could go close to $2 a litre by the end of 2008. So as everyone tries to keep the family budget from going bust, just what is the best option for motorists right now? In the simplest terms it's a case of either reducing the cost of the fuel or reducing the fuel consumed. In the first instance the answer is simple with LPG offering motorists major savings. LPG prices are currently around half those for petrol and according to Phil Westlake, industry development manager for LPG Australia, the savings on offer have never been greater. Motorists also get the benefit of a $2,000 federal government grant to convert their cars. "Even without a $2,000 grant, a motorist who converts a six-cylinder engine to run on gas will recover their conversion investment in under two years, assuming they travel 25,000 kilometres per year and their conversion cost $3,000," Mr Westlake said. "Factoring in a $2,000 grant towards the conversion, you would recover the conversion cost in only seven months." But gas isn't the only option. There's now a range of cars in the light model segment that cut petrol consumption to as little as six litres per 100 kilometres including the Toyota Yaris, Honda Jazz and the Mazda 2. Even more miserly are the hybrids, like the Toyota Prius and the petrol-electric version of the Honda Civic. Both can cut fuel consumption to around four litres per hundred kilometres, turning the petrol engine off whenever it's not needed, either stopped at the traffic lights or cruising the highway. By comparison the Prius can travel about 85 kilometres on $5 of fuel, even at today's prices, while the traditional Aussie six-cylinder will be lucky to make 30km. Not surprisingly, Holden has announced plans to have a hybrid Commodore on the market within about two years. Diesels also offer strong savings, some increasing the range of a medium-sized sedan to more than 1,000 km on a single tank. The oil-burners have long been embraced in Europe, and are slowly growing in popularity in Australia although local motorists, for some strange reason, are still slugged more for diesel than unleaded petrol. But if the ultimate in low cost motoring is what you're hankering for then you might have to wait some time or get yourself out on the road between Darwin and Adelaide every two years when the world's fastest solar-powered cars showcase just what can be done with the power of the sun. True, they're not the most comfortable or sturdy vehicles on the highway and there's no room for passengers or a set of golf clubs. But they might just prove to be the future of personal mobility, if not this century, in the centuries to come. AAP