State and local officials sweetened the pot of incentives they have dangled in front of Toyota Motor Corp. as it ponders the fate of the NUMMI auto plant in Fremont.

The enhancement of the previously disclosed package of financial inducements includes a facility to enable improved shipments to the New United Motor Manufacturing Inc. factory, an application for federal stimulus money, and the potential for NUMMI to slash its electricity bills.

The prospective measures were sketched in a letter sent to the president and chief executive officer of Toyota Motor, Akio Toyoda. The letter was signed by Gov. Arnold Schwarzenegger, Fremont Mayor Bob Wasserman and Alameda County Supervisor Scott Haggerty.

“We understand that under present circumstances you are facing difficult business decisions,” the governor and the two local officials wrote. “Accordingly, state, regional and local authorities would like to assist Toyota to maintain manufacturing operations in California.”

Toyota says it will soon decide whether it will shut the NUMMI plant or continue to use the plant to build vehicles at the factory, which for a quarter-century was a joint venture between Toyota and General Motors Corp. Toyota is being forced to make a decision after GM decided to abandon the factory in July.

The package of incentives is not an 11th-hour desperation move by California politicians who hope to save NUMMI’s 4,700 jobs and millions of dollars in annual economic activity, Wasserman said.

“I don’t think this is a last-minute Hail Mary,” Wasserman said. “But I won’t say that I’m confident this will work.”

Among the proposals:

n”‚Union Pacific will direct shipments directly to NUMMI from Lathrop. The state is seeking $20 million to build an inter modal complex at NUMMI.

n”‚The state legislature is working on creation of enterprise zones and other tax breaks.

n”‚The city and county will seek $29 million in federal stimulus money.

n”‚Regional officials will allow NUMMI to buy electricity from a lower-cost provider, yet still use PG&E transmission lines.

“I’m not convinced Toyota is leaving NUMMI,” Wasserman said. “But at some point, we need to hear from Toyota to see if we are on track or off track, or what we still need to do.”