Active vs Passive Crossovers

I Saw a topic that was like this but it didnt answer my question I had brewed up. A guy that was big into car audio at one point told me today that passive crossovers are not efficient. They start leaking out frequencies that the drivers are not suppose to be getting. He told me that active crossovers are the way to go without a doubt. I didnt know how true this was so I've come here. I understand the tuning aspect of active crossovers, but is the signal and frequency division that much better? Arnt passive crossovers designed to go with the specific speaker if they came with them?

It took some searching, but I finally found a relevant post by my boss, Dan Wiggins on this subject.  Here's the quote:

"Originally posted by DanWiggins

A properly designed passive crossover is always a better solution than a stock/generic active crossover. One needs look no further than the following graph to understand why: http://www.adireaudio.com/Files/Dan/XOResponse.gifThis is the frequency response of a passive woofer network I developed for a high efficiency monitor. It compensates for several frequency response problems in the drivers, and results in a relatively smooth (+/- 2 dB) final frequency response of the driver plus crossover. Kind of hard to do with a stock/generic active crossover. You'd need at least a 4 band fully parametric EQ to get this type of response (a 1/3rd octave EQ won't quite work, because of the Q of the peak at 1.8 kHz).A well-designed passive XO will do more than just "roll off" the driver. It will include equalization (often called 'voicing') that will smooth the driver's response, and provide any level matching as needed.And as far as "impedance error" problems, you typically reduce them with passive crossovers. Again, a well designed passive crossover will take the wide swings of the impedance of the raw driver, and lower them to a very small range. The amp will typically see a much more stable impedance with a well designed passive crossover than with just the driver by itself.Overall, unless you have quite a bit of EQ available (1/3rd octave EQs, parametric EQs, etc), as well as a decent active XO and more amp channels, I'd take a well designed passive crossover to start with.Dan WigginsAdire Audio"