Meryl Streep and Martin Short Arrive in Same Car to 'SNL' Filming

Meryl Streep and Martin Short swear they aren't dating ... but, they're certainly spending a lot of late nights together -- pulling up to "Saturday Night Live" in the same car.

The two stars pulled up to 30 Rockefeller Plaza last night ... about 10 minutes before the show was set to kick off.

It's a short clip ... the two jump out of the car together, and Martin exchanges pleasantries with a man who appears to be a security guard.

Meryl says hello to some waiting fans, and they walk straight into the building. As always, there's no PDA between these two ... but, it certainly won't stop rumors about them dating from flying.

As you know ... Meryl costarred on the third season of "Only Murders in the Building" with Martin, Selena Gomez and Steve Martin -- and, sparked dating rumors with Short soon after.

A rep for Short told us last year that the two aren't dating, and they're just friends ... but, Meryl and Martin are constantly together -- recently appearing at multiple 'SNL50' events together.

BTW ... looks like Meryl and Martin didn't just hit up 'SNL' last night -- 'cause Jennifer Lopez posted a pic from behind-the-scenes of the Broadway show "Oh, Mary!" alongside them and a few other famous faces.