I recently added Auto-RX to a 2008 Lexus ES 350 with 20,000 miles. It's my understanding that Toyota/Lexus is notorious for sludge prone vehicles, hence, my need for Auto-RX. To my surprise I'm experiencing a .75 to 1 mpg increase during this cleaning phase. Is this a unusual occurrence? Can I expect this to continue during the rinse phase or even after I've completed rinse stage. The car also seems to have more power on acceleration. Purchasing this product seems to be well worth the expense? Your thoughts please? Thanks.