Under California’s zero-emissions vehicle (ZEV) regulation, 2003 was supposed to be the year that thousands of nonpolluting cars hit the road — but on Friday, the state’s air quality officials proposed amending the regulation to postpone the deadline by a decade. The proposal seemed to be an acknowledgement by the California Air Resources Board that the technology does not yet exist to make the cars attractive and affordable. Although cars are getting cleaner, especially in California, there are still no competitively priced, emissions-free models on the market. The proposed changes would allow automakers to put off ZEV requirements until 2012, but require them to produce more hybrids and super-clean gas-powered vehicles between 2005 and 2011. Both environmentalists and car manufacturers have expressed dissatisfaction with the board’s suggestions; the former want the original ZEV requirements and deadlines maintained, and the latter want them scrapped altogether.