FWIW I fixed my sliding floor mat problem. Home Depot and probably everywhere else sells 2" velcro discs. They don't stick right to the bottom of the floor mat, but I sewed mine on with a medium-heavy needle and thread. Positioned them directly over the screw-in velcro holder thingies on the floor. Perfect!

 

MY floor mat drive me crazy please picture.

 

Do you have the black discs screwed into the floor of your car? They have the rigid plastic component of the velcro. So, you sew the fuzzy disc of velcro to the underside of your mats and they stick together like the OEM ones do.