Does the PWV-SB12 need a separate amplifier?

No. The enclosure includes a built-in DSP amplifier, so you only need power, ground and a signal source. That simplifies the install compared with a passive sub and amp.

How is it different from the 10-inch BassRev?

The 12-inch version uses a larger woofer for more cone area and stronger output. The 10-inch model fits tighter spaces. Both share the shallow sealed cabinet and OPTIM Sync DSP.

What does OPTIM Sync do?

It is a dynamic bass boost algorithm in the amplifier that extends low-frequency response from the preloaded woofer. It is tuned by Alpine for this enclosure, so you do not set it yourself.

Will it fit in a small trunk or under a seat?

The shallow footprint is designed to fit where full-size boxes will not. Measure your mounting area against the enclosure dimensions before buying, since depth and height still matter.

Is a sealed shallow box as loud as a ported one?

Generally no. A sealed shallow enclosure gives tighter, more controlled bass and saves space, but a large ported box typically plays louder at the lowest frequencies.