Nice one Jarre, beat me to it lol
In an ideal world, you’d be looking to set up a system in the car that is like a home cinema surround sound system with separate amps & different speakers
At home, I have a surround sound system made up of hi-fi separates, so I have:
Amp
Active Subwoofer
Front left & right full range speakers (incorporating mid bass, mid range & tweeters)
Rear left & right satellite speakers (incorporating mid range & tweeters)
Typically though, unless you’re going to rip your car apart to do a professional aftermarket install, putting in a sub in the boot, mid bass, mid range & tweeters, then to just get a better overall sound over standard, just replace the stock mid range with either:
A 2 way/3-way co-axial, or, an aftermarket mid range replacement
Another good pointer when choosing what to go for is to look at the range of frequency response the speaker is good for, the wider, the better (I think)