A policeman disarms a bomb in a car while girl is in driver seat. She is embarrassed because to is not wearing panties

I'm not sure about the panties, but...
Live Wire (1992)
Starring Pierce Brosnan, Ron Silver, Ben Cross
IMDb synopsis:
When a senator is killed in an explosion, the FBI investigates. The agent in charge is Danny O'Neill, who is separated from his wife and behaving very erratically. Initially, the investigation doesn't reveal what kind of explosive or even what was used to detonate it. It doesn't help that they have to report Senator Traveres, the man whom O'Neill's wife has been seen with and whom he also assaulted. After another senator is killed, his driver, who was responsible, is caught and brought on trial. At his hearing, another explosion occurs after the judge drinks some water.

Live Wire (1992) - IMDb (http://www.imdb.com/title/tt0104743/)

As I recall, the movie opens with Danny deactivating a bomb under a driver's seat on which is seated a beautiful young woman. They make jokey-talk to lighten the tense situation. It's possible that she says something about lack of panties; I simply don't recall that.

Blown Away. With Jeff Bridges, but she's at her desk.