Im assuming you are going active? If so, so long as you have enough flexibility with time alignment, crossover points, slopes, independant gains, and hopefully independant L/R EQ, you should be fine.
The important thing to note is that EVERYTHING comes into play when attempting to recreate stereo imaging in a hostile environment like a car. Which tool is more effective depends on the vehicle, install, and drivers. The more of the mentioned tools you have, the better chance at success.
I would suggest doing some experimentation with the drivers to see if you can get a concrete foundation with the install FIRST. You can do this by playing with different positions, angles, and relative phase (though I usually discourage using this option). Then use one of the many tuning guides found here to start.