My car was recently only getting around 23 mpg driving locally, not traffic jams. At 37 mpg combined official I'd expected about 30 mpg. The car had been serviced, oil and filters, and is runnning fine. I've always use supermarket unleaded but decided to try BP superunleaded. I also put in some redex fuel/additive injector cleaner. Its only been a few days but I've noticed the fuel gauge not moving down as fast compared to before. Its too early to tell whether the mpg has increased and whether the slow moving fuel gauge is just psychological. Would putting in redex and superunleaded help mpg? Is it better to use just one rather than both, would superunleaded have redex agents in already? I've heard redex cleans the injectors? The cars done 103k miles. I haven't noticed an increase in performance.