Photogs snapped the couple caught in rush hour traffic Wednesday -- and they were rolling in completely different vehicles. BC was piloting her Porsche and Ye was riding shotgun in a Cybertruck ... both seemingly happy and healthy after what sounds like a tough night.

Hard to tell what Bianca's wearing here -- unclear if it's her usual level of sheer or not -- but, she's got her eyes firmly fixed on the road while waiting at traffic lights in her sweet ride.

Ye, meanwhile, was looking at his phone and chatting up the other two dudes in his own whip. The trio seems totally unbothered by Kanye's potential legal issues -- which may or may not amount to anything as LAPD delves into their investigation.

We broke the story ... cops are investigating Ye after he allegedly hit a guy who his team claims sexually assaulted Bianca. Law enforcement sources tell us Kanye and Bianca took off after the alleged altercation, and the guy claiming Ye hit him didn't need medical attention. Ye's team says the man in question had assaulted Bianca.

It's interesting Ye and Bianca are already back out in public so soon after something like that ... and yet they are. From the looks of it, the whole saga is the furthest thing from their mind.

Remember, this isn't the first time Ye's been in the crosshairs of the legal system -- he's been accused of getting handsy with people in public in the past ... but he's never been criminally charged over the past episodes.