Wow for 30,000 miles I've driven my poor turbo scooping miata all over the place. NYC, Philly, DC, none of which have the bestest streets. NYC's are probably the best actually. That scooper has smashed into so many speedbumps, undulations in the road, highway dropoffs (while they are repaving there's that ledge thing after the asphalt eater goes through), driveway entrances, exits etc. It's scratched up but it's still there. I had to redo the bolts with some different washers but it's stayed there for about a year and a half no problemo. No grass, but the ****** is on there and holding. As for it's effectiveness, I have no clue but I like how it looks. My car is on kyb and fm springs. Far from slammed, but the scooper smashes all over the place. So does the underside of my front bumper though.