A Google search for BG Products, or for example BG44k, BG's best-selling premium fuel system cleaner, brings up many, many positive recommendations. Here are just three testimonials:

(Had his 2012 Mercedes CLS350 CDi circa 70,000 miles serviced with BG Engine Performance Restoration flush and BG 245 Diesel Fuel System Cleaner) -- In truth, I first thought it hadn't made much difference other than giving the car a little more poke than usual. However after a few trips circa 120+ miles it was evident that the car was running much more economically. No word of a lie the car is running 3 to 5 mpg better now if not more and proof is that it has increased the overall mpg, which you will know takes some doing - John, Worcester

Last august I bought a Smart ForTwo expecting to get a good fuel economy, only having just over nineteen thousand on the clock. Didn't happen – only about 41 to 43mpg on average and so agreed to a BG Fuel Saving Service. Was I surprised afterwards. After a short trip of about 18miles I returned to the garage and said "Where did you put the second turbo?" as the car had never responded like that before. Well folks, see the improvement getting even better and not over just a short period but over 1,381 miles so far and I will still be checking and reporting the results so keep looking. Tank 1: after 260 miles 43.03mpg - Tank 2: after another 277 miles 48.40mpg – Tank 3 after another 219 miles 46.20mpg - Tank 4 :after another 129 miles 45.81mpg - Tank 5: after another 276 miles 49.28mpg - Tank 6: after another 220 miles 52.13mpg - These are the results so far and I would like to say well done and thank you BG products for turning my car around. Loving the performance and didn’t expect these results. Awesome!!!!! - George

(Mercedes Diesel with carbon build-up affecting the DPF, restored by BG DPF & Emissions Service) – This car has been well looked after and always had its services etc. But I’ve honestly never enjoyed driving it so much. It’s now a pleasure to drive instead of a burden. The car’s like a new one - Baz Cooke