a coloured sticker on its windscreen which noted the day on which it could not be used. Infringements were punishable by a fine of up to $400 (approx. $2500 in 2022 dollars). Thursday was the most frequently chosen carless day. By the time the regulations were suspended, 43% of registered vehicles had exemptions. A black market for exemption stickers and imitations of them quickly developed, weakening the effectiveness of the scheme. There was also a distinct problem in inequality—households that could afford to run two cars could simply choose different days for the two cars and continue to drive on all seven days as before. Implementation The carless days regulations are secondary legislation under the Economic Stabilisation Act 1948 and therefore did not require approval from parliament. Carless days were suspended in May 1980, revoked in December 1980 and in 1981 replaced with petrol rationing legislation (the Petroleum Demand Restraint Act 1981) that can be invoked in the future. Response Surveys showed that 5-10% of the population bound by the rules drove regularly on their carless day. Journalist Richard Griffin said that it was a bit like drunk driving - if you could get away with it you did. There was no stigma attached .... There were 3,136 successful prosecutions against those who broke the carless days rules. It is estimated that approximately 0.2% of the people breaking the rules were caught and prosecuted. The first person fined was Gordon Marks of Christchurch, who forgot that at 3.45 am after a post-party nap in his car his "car-less day" had started at 2 am. He was fined $50 rather than the $400 maximum fine. Impact The government claimed that the plan reduced petrol consumption by 3%, while independent analysis estimated a reduction of 3.6%. Those that were subject to the scheme reduced their petrol consumption by 5%. It is estimated that the price would have had to rise by 87.5% to achieve the same reduction in petrol consumption achieved by carless days. Carless days led to notable mode shift for work and shopping trips. While cars continued to be used for the majority of work trips on carless days (from 88% to 66%), there was a notable increase in car pooling (5% to 19%), bus (2% to 7%), motorbike (2% to 7%) and bicycle usage (7% to 12%). Shopping trips while still predominantly done by car on carless days (88%