It's been many years since my last "new" car purchase and I had never even heard of this etching/nitrogen fee until yesterday. I just want to share my brief experience on the subject.
My wife and I are ready to purchase a new Hyundai and happened to come across the colour we want at an out of town dealer yesterday afternoon. We made an offer to buy the vehicle. The salesperson came back with a reasonable counter-offer but also informed us of an additional $500 charge, not shown on their website, for nitrogen filled tires and vehicle etching. We just looked at each other... nitrowhat? She went on to explain the benefits of both features and stated that "all vehicles arrive at the dealership already etched and nitrogen filled". Also adding "I have no idea why they don't show this charge on the website". Confused by this additional charge we decided not to negotiate any further and leave our purchase for another day. As we were saying our "we'll think about it's", the salesperson did offer to see what she could do about the $500. We left before that happened.
I started searching this site for information on nitrogen/etching as soon as we got home.
I'm pretty certain that we will still buy this car somewhere but more than likely from another dealer. Our next offer will start $500 lower than yesterday's in anticipation of this happening again.
Thanks to the regular posters on this site. Awesome information here.