Paul Stanley is opening up about his former KISS bandmate Gene Simmons after last week’s scary Malibu car crash — telling TMZ it’s a flat-out miracle he walked away unharmed.

TMZ caught up with Paul in L.A. Monday … and he admits that when Gene lost consciousness while driving down Pacific Coast Highway and crashed his SUV into a parked car in Malibu, he could have been killed — and it was terrifying for him.

Catch the full clip — Paul gushes about how well Gene’s doing … and even spills the lesson he hopes his bandmate took from the whole scare!

At the end of the day, Paul’s concern comes from a good place — he’s clear they’re always in high spirits and still kicking it together.

Paul’s concerns mirror what Gene’s family is saying … his wife Shannon told TMZ it’s time for some lifestyle changes after the recent car accident, admitting she doesn’t want to be riding shotgun with him anymore.