in-stant fill

I was looking at the stant site. I was looking at these gas caps that you don't even have to remove the cap just stick the nozzle in. Has anyone ever used on and do they actually work
Here is the site
http://www.stant.com/brochure.cfm?brochure=3089&location_id=5009

It claims to comply with OBDII emissions, but I'd still be worried of it causing problems with the EVAP system.

Timely question - I was just looking at these yesterday. I passed for the same reason Blazee gave. I might try it for kicks. The worst it'll do is turn on the light. I hate having my cap dangling down hitting the paint.