Carless days was a petrol demand reduction plan active from July 1979 to May 1980 introduced by the New Zealand government amidst the 1979 oil crisis. Introduced by the Third National Government of New Zealand, the plan prohibited owners of private petrol-powered vehicles to drive on a self-designated day of the week. The enabling regulations were one of several attempts to help the New Zealand economy after the oil shocks of the late 1970s—other such policies included the Think Big strategy. Background International oil prices increased by a factor of 15 in nominal terms or a factor of 7 between 1972 and 1980. Despite price controls on petrol at the time, prices in New Zealand also rose rapidly from $0.10 in 1972 to $0.62 in 1980. The last price increase before the introduction of the carless days regulations was a 24.8% increase on May 17 which in itself is estimated to have contributed to an 11% reduction in petrol usage. Prior to the introduction of carless days, the government had implemented other measures to reduce petrol demand. One measure was the reduction of the speed limit from 100km/h to 80km/h in December 1973 during the earlier 1973 oil crisis. The lower speed limit remained in place until July 1986. Another measure implemented in February 1979, was the ban on the sale of petrol on weekends to most motorists with exceptions for emergency situations and essential users. Several countries including Switzerland, the Netherlands and West Germany implemented similar carless Sundays during the 1973 oil crisis. The government also encouraged the use of alternative fuels like Compressed natural gas and Liquefied petroleum gas. Interest free loans were provided for the conversion of vehicles to run on gas and subsidies were provided for gas refueling infrastructure. By 1985, nearly 7% of the car fleet had been fitted to run on CNG. According to Bill Birch, the minister of energy at the time, the government considered rationing, but chose carless days instead as it required less regulation and was easier to start and suspend quickly. Plan In this plan, the owners of most private petrol-powered motor vehicles under , with the exception of motorcycles, were required to refrain from using their car on one day of the week, that day being designated by the owner. Exemptions were issued for essential services and those with no alternatives to using their own vehicles. Each vehicle displayed