This is one of the few well documented, safe and reasonably effective products you can add to your gas tank that will not harm any part of your engine and perhaps help various issues depending on what your car needs.  It is safe because it has been used for years in Chevron gasoline.  The highest concentration of it are in the premium grade.  There have been lots of studies done on Techron.  The only difference between a bottle of this and the Techron in the pump at the gas station is that the Techron in this bottle is a much higher concentration. The reviewer who said that Chevorn stations were disappearing did not know what he was talking about and as to his manual stating not to use additives that may or may not be the case but for Techron since it is in pump gas it makes no sense this product would be included.  It is designed to clean deposits in fuel injectors and carbs and to some degree help clean or prevent buildup of deposits on valves.  It may nor may not increase MPG, that is entirely dependent upon the issue you are having and how much a detergent added to your gas can clean. If your fuel injectors can have a better spray pattern then perhaps you could see minor increases in MPG.  It is more likely to help an engine run and idle smoother and have power closer to what it was new if the fuel system has become inefficient due to becoming dirty with deposits. In many instances it can help clean deposits to an extent where there is a noticeable improvement in how your engine idles because it has helped to unclog your fuel injectors.  Again it certainly is one product that will not in any event harm your engine. It also will very likely help keep those deposits from becoming an issue in the first place if used on occasion.  However this, like any other gas additive can only do so much. It is reasonable to try using it before moving on to a more expensive repair, but no gas additive can take the place of a mechanical cleaning or replacement or a fuel injector or repair of a damaged engine.  So if you are going to use a cleaning fuel additive this is one of the best and the safest to try.  Just remember there is no "engine rebuild in a can" and the bulk of products such as oil additive mask serious wear issues at best.  If you have relatively minor issues that could be helped by cleaning of the fuel delivery system this is one of the first easiest steps to take, along with changing fuel filters and any other maintenance that your car may need such as replacing spark plugs.  If this does not work there are machines at shops that are made for cleaning fuel injectors and related systems such as MotoVac which runs a cleaning fluid in a closed loop for a long period of time.  That is a step up from adding something to your tank. If that fails than a mechanical remedy is needed.  The only other two products I would consider using are made by Redline and Lucas.  They make good products in general and have had good reviews on their fuel system cleaners.  So feel safe trying this but don't expect miracles.  Proper engine maintenance is going to be your best and lowest cost way to avoid repairs and keep your car running like new more than any other thing you can do.