One of the first interior quirks I picked up on in the short time since I've had my 2003 Vibe is the rear cargo/convenience mat. While it looks awesome, it slides around and is virtually impossible to stop no matter what you throw at it. However, I have worked on cars for decades, both body and mechanical, and after careful thought, I came up with a solution that basically is what the vehicle should have had to begin with. Below you will find the necessary tools and supplies to finally make that mat stay in place.
You will need:
A drill
3/16 drill bit
Dorman Panel Retainers 799-135 (available at most auto parts stores)
A tape measure
Remove the cargo mat and open the cargo lid. Underneath you should see circles all over the bottom. Count three circles over from the left edge and use the tape measure to find the points located at the 4 inch mark and 20 inch mark as pictured below. Using the 3/16 drill bit, drill through the center of those two circles. Repeat on the right side, except this time count three circles over from the right edge.
Lay the cargo mat on top of the cargo lid. Line it up so it is straight to the rear edge where it is lifted; that edge is more critical. I didn't list it, but I used jumper cables to clamp the mat to the lid while I performed the next step. As long as it clamps tight, use whatever you can find.
Drill through the holes you drilled in the cargo lid from the underside again, this time going through the cargo mat. Once each is complete, take a Dorman 799-135 clip and on the mat side of the lid push it through the hole until you cannot push anymore.
Now you have a professionally installed cargo mat! You can still open and close the lid locks, open and close the lid, lower/raise seats, and carry cargo without having to worry about the mat again!