WASHINGTON — Amtrak is trying to gin up new business by offering $100 in free alcohol to customers on some overnight trains. The national passenger rail company is making the unusual offer to promote a new high-end service being offered on a tryout basis for certain sleeper car trips.

Members of Amtrak’s guest rewards program — the railroad equivalent of frequent fliers — can get a $100 per person credit for alcohol between November and January.

At about $6 for a house wine, or a top shelf scotch for $7, that credit could fuel a long ride. The credit wouldn’t go nearly as far for, say, a $250 bottle of Dom Perignon.

Amtrak spokeswoman Karina Morero said the free alcohol aims to entice people to try the new, high-end sleeper car service.

Some train operators have recently begun examining whether to continue allowing alcohol on trains. On Long Island the commuter rail company considered ending alcohol service out of concern some passengers might disembark at their destination and drive home drunk. The proposal was shelved after some patrons opposed the idea.

Mothers Against Drunk Driving said it wants assurances that Amtrak won’t overserve passengers.