I am wondering about other's driving experience. This is probably the best Cadillac I have owned since my 89 Eldo. I am curious about what other owners have experienced. Some how I assumed that regular unleaded was ok since my 02 Seville used it and was surprised to find out this one likes Premium. I am on my second tank of regular but will change at next fillup. Will performance and mileage improve? I have noticed around town, the slightest incline causes a pretty agressive downshift, very sporty but makes leisurely cruising almost impossible. The downshift usually happens at about 25MPH 1100RPM and suddenly I'm at about 2000RPM and on a long slow hill it becomes a little jerky as it shifts up and down. I am not complaining just wondering is this what is expected. It's been so long since I have owned a performance car I might have lost touch with what that driving experience is. So far no problems and loving the car. While I'm at it, any opinions on washing and waxing? I put on a coat of a high tech polymer over the weekend, didn't see much of a difference in shine. What are you all using?