There is on such thing as a car Subwoofer bassbox the word sub come from subsonic below the human earring range.
The inside of a large car in only about 15 feet max across the diagonals, now look at this frequency to distance example 50 Hz has 22.6 foot wave length and 25Hz has 45.2 feet wave length. So a 15 foot car will have a maximum low frequency of its physical internal dimensions of about 80 Hz and that is well within the earring of even an old age pensioner. The audio sound waveforms lower then 80 Hz are just physical to large to fit in to a small car. So that has proven the point that you can not have a car subwoofer bass-box well unless you had a covetable car pulling a 20 foot trailer and had the big bass sub woofer mounted right at the back of the trailer then that mite be ok.
So next time you bump into Mr. Car tires wheel spinner and you hear him giving the full Monty about his boy race Alpine car subsound system, you can now shoot him one in the foot with what I have just told you.
I must say this about car subs in my Subwoofer bassbox review they are first class in appearance, but perhaps not the pink one in the speaker picture unless your a new disco girl racers.