I have plenty of experience with BG44K. Its not a magic mileage increaser, but it will restore mileage lost because of a dirty intake system. Its a very powerful cleaner. My standard method is to use a bottle of Techron once a month and then a can of BG44K just before an oil change. I've done this since the early '90s on the advice of a mechanic friend of mine and have excellent results.

YMMV, of course.

__________________
"It's not about how fast you can go, but how well you can go fast."

Bob in Richmond

'97 S320 (LWB), Ruby Red Metallic, 73k miles
'97 S420V, Smoke Silver Metallic, 155k miles