In most circles, a Chrysler 300 isn’t really considered a good first car, as they—and many Chrysler models—are known to be somewhat unreliable and typically do not last as long as some of their competitors (e.g. the Dodge Charger, Chevrolet SS, etc.). You’ll definitely want to stay away from the 2006 model year, as there have been numerous cases of premature engine failure before 100,000 miles.
Of course, this doesn’t mean that any given Chrysler 300 will clunk out at or before 100,000 miles—it just means that the evidence suggests it isn’t out of the picture.
That being said, if you’re serious about driving and plan on owning the same vehicle for the next seven to 12 years, the Chrysler 300 could be a good first car as long as you keep up to date on all maintenance procedures.