When I first used Z-Max I got a 5% increase in mileage. I called and they immediately offered a refund of my costs. I declined their offer and used it another 6 months. My mileage had increase to a 10% gain. This was with two cars at approximately 15k miles each. At a cost of approximate $0.002 per mile it saves about 10% or $0.006 per mile ( at $1.50 per gallon). I've just e-mailed them and will add their comments about the FTC complaint when I get it. Roger

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Roger
1983 300CD 246k sold
1998 C230 52k
1980 450SL 75k needs AC
1999 Subaru Outback Ltd 43k