I've had great results using Star Tron gas treatment.  The product was recomended by a person I purchased
my BMW motorcycle from.  I have a fleet of older cars, and I've seen better fuel economy and  they all seem to be running better now that I use Star Tron. We are also using this for our outboard Honda engine. 

Thanks again,

Claire  Radke 
p.s. Ive included a photo of the BMW