Some of the newer cars on the market come with a great sound system. Older cars may not. There are a few simple things that you can do to take your sound system to the next level. Replacing your speakers and head unit are a great start.
Lets face it if you want to hear a full spectrum of sound from your music you will have to replace your front and rear speakers, add a sub and amp and change your head unit.
For your head unit you need to check its power output so that there is a synergy between all of your audio equipment. This is so you don’t drain your battery and that you have adequate power to your speakers to get the right sound from them.
6×9 Co-Axial speakers are great for your back parcel shelf and you can get some at a reasonable price. Couple that with some component speakers that can harness the mid and high range frequencies and you have a strong foundation. All you have to do after that is include your sub and amp and you are ready to rock.