Is my 1987 Mercedes Benz 260E fit to transport me from SF to Seattle?

This car has died innumerous times. The alternator has been replaced and the grandparents say it drives fine. But they don't know anything about cars and they only drive it around town. When I jump it, the car alarm goes off and last night the alarm went off and then turned itself off without any antagonization. Basically I don't trust this vehicle at all but my girlfriend thinks it's fine to drive over 1600 miles in the middle of summer. Give me your two cents educated and intelligent people!!!! I don't want some jackass answer you pulled put of a movie......all things considered thanks a lot people