Is the 4 peak HP rating the same as running power?

No. Peak HP is a marketing figure measured at maximum motor load. The 900W input rating is the more useful number for judging suction and current draw.

What does the self-cleaning filter button do?

It is a one-button system that clears debris from the dual filter to keep airflow going. It reduces the need to stop and manually clean the filter mid-job.

Can it pick up both water and dust?

Yes. It is a wet/dry vacuum with a 5.8-gallon tank, so it handles liquid spills and dry debris like sawdust. You switch setups between wet and dry use.

What comes in the box?

The vacuum, a 1.25-inch by 7-foot hose, a multi-purpose nozzle set and three-piece extension tubes. The 9.8-foot cord is attached.

How does it compare with a 12-gallon shop vac?

It is smaller and easier to move, with a narrower hose and less capacity. A 12-gallon model holds more debris and usually offers a wider hose and blower port.

Is it good for car interiors?

Yes. The 1.25-inch hose and nozzle set reach into footwells and seats, and the casters roll around the vehicle. The compact tank helps in tight spaces.