Anyway, I found I had just enough room for an 18" wide dual driver autotuba in the boot (trunk). I went for dual drivers as I'm using a 4 channel amp and have 2 channels for the sub. Also, I sometimes like to use it in the house, and the extra power handling helps...

Anyway, I've went from a vented 12" pioneer sub to this. The Pioneer was getting over twice the power (160Wrms), and the AT actually gives more output with only 40Wrms going to each driver. Amazing. The AT sounds nicer to my ears, but it also makes my rattly French interior rattle even more... I need to get round to sorting this...
I'm running a 12db/oct butterworth LPF that is fixed at 120Hz (it's built into my amp), but I'm soon gonna switch to a 4 channel class-d amp that will give almost twice the power (75Wrms per chan), and I'm also gonna have a go at making a 24db/oct filter which may give a better sound. We shall see. Even with 40Wrms per chan this thing is very loud, so 75 is going to be way more than I need. I would have to get ear protection if I was ever going to try 100w per chan!

Overall, I was impressed when I tried this in the house, so I already knew it was gonna work well in the car. Tight, clean bass... You can feel it as well as hear it. I like a lot of bass heavy music (dubstep, etc.), and this really suits
If anyone with a smaller car is having doubts, build it anyway. It will should fit with a bit of effort...
