[woodman]

I'm guessing that you're concerned about a place that has no parking authority, highway patrol, corporate security, nosey neighbors - because an abandoned vehicle won't last more than two days otherwise. There is a reason why assassins have historically chosen guns over bombs, and it isn't due to a lack of technology that places distance between themselves and the target. Like most important things, when assassinating somebody, you want to eliminate as much uncertainty as possible. That is pretty much the opposite of just leaving a bomb somewhere and crossing your fingers. Also, leaving a lot of bombs all over the place increases the odds of detection.