Kristen Stewart & Stella Maxwell Take Sexy, Death-Defying Pics

Kristen Stewart enjoyed the benefits of dating supermodel Stella Maxwell by playing photographer for her during an impromptu photo shoot ... while hanging out of a moving car ... in lingerie.

Well, only Stella was showing off her bra, but Kristen hung out the window too Tuesday in New Orleans ... to snap what we can only imagine is that perfect Instagram shot.

Great view for people in the car behind them.

Kristen is fresh off her directorial debut in Cannes. We're guessing it went well, based on this celebration.