I saw the occasional bad review but thought what the heck should I do because it's cheap enough. The product came quickly and the support team helps faster. I don't know what all these bad reviews are for as my Lincoln Aviator 03 works day and night! Bad reviewers obviously installed incorrectly (maybe computer not restarted / wrong cables contacted with add.). I can't say much about the best mpg because I enjoy accelerating so much. So impressed that I bought it for the whole family. In fact, a few days went by and consumption increased from 14-16mpg to 17-20. That was ONLY the chip, no mods, the whole stock car. Installation was so easy a caveman from an insurance ad could do it. Ordered a low temperature thermostat and cold air intake. I can't wait to see what's next. Make no mistake, the product pays off!