Just thought I'd pass along my recent experience on this for what it's worth. Last night I finally tried out my bottle of Meguiars Gold Class Leather Cleaner and Conditioner. I had the bottle for a year and had been putting it off because of warnings on the label "test for colorfastness" and because I'd heard that using it can be a bit tricky. I've had my 2005 coupe for two years now and had only used wipes up to this point.
I did test a small area of the seat and found it to be ok and continued on. I used one microfibre towel to apply the liquid (it's pretty runny) and another to do the final wipe. I worked in sections of the seat from seam to seam and made sure to wipe previous areas a second time when I did the section next to them.
I'm happy to report that the stuff is amazing! It went on easy enough and you could sure see the dirt coming off on the towel, and then it wiped off beautifully with the second towel. The resulting surface looks and feels totally rejuvenated, no greasy of glossy residue, no white powder in the seams - the seats look like new (or better).
That's it for the answers - now for the warnings and questions. Do not use it on the doors!! I thought the middle panel of our doors was leather and I'm not sure if it is or it isn't, but I nearly ruined it! I started wiping the cleaner on and immediately the color began to change. I quickly grabbed an Armor-all wipe and, with great scrubbing, I seem to have saved it. I've used leather wipes there in the past with no problems and also on the steering wheel, so I'm not sure what's up. I was too chicken after that to try the wheel.
So, my questions are: Are there any other areas of the interior that we know are leather? Does anyone have experience with a better applicator? - the MF towel was great for wiping off but not the best for applying. Also, I dribbled a bit on the carpet and it seems to be leaving a dark spot - any suggestions?
To sum up - the product is excellent, easy to use and the results are amazing!