People who go to extreme lengths maximize their fuel efficiency of their cars. Some Hypermiling techniques are illegal but are still practiced by A few people, not to cope with the situation with rising fuel prices.< Termnewline < termnewline > > include A few common Hypermiling techniques perform basic maintenance on the car to increase its performance, to make sure that the tyres have the correct air pressure and at constant speeds of travel. Include more drastic and dangerous methods add chemicals to the fuel supply or 'Design' - Right away behind a large truck or similar vehicle drive to reduce the air resistance.