Auto-Train Corp. announced yesterday it is cutting fares on its trains carrying passengers and their cars btween suburban Lorton Va., and Florida and taking other steps to boost ridership.

Effective Jan. 5, the one-way fare for each car eill be cut 23 percent from $155 to $119. The fare for adult passengers will reamin $70.

Auto-Train will alos offer a 20 percent discount on round trio fares and a group rate of 20 percent off for groups of 15 or more persons.

The fare cuts are acompanied by a new consumer advertising program and a promotion campaign aimed at enlisting travel agents to sign up passengers.

Auto-Train has been plagued by poor ridership for much of the past year and the lack of passengers has contributed to the severe financial problems of the Washington-based railroad.

Auto-Train president Eugene Kerik Garfield yesterdau said the trains are sold out southbound for several days between Christmas and New Years, but declined to provide specifics about traffic.

"The bookings are coming in stronger this year compared with last year, picking up at a faster rate, but beginning with a lower base," he said.

Auto-Train executives have previously blamed declining ridership on the competition from discount air fares.

Garfield said a decision made recently to aapeal made recently to appeal to the luxury travel market by offering service on the company's private railroad car has already produced 25 reservations.

Previously reserved for Auto-Train executives the rpivate car is now available to anyone willing to pay $1,500 one-way. The car carries six persons in luxuty facilities that include a living room, dining room, three state-rooms with private baths. The fare alos uncludes two automobiles.

Garfield said the company is "making good progress" on effrots to restructure its debt and obtain new financing that will ease its heavy interest costs.