A 110% money-back guarantee actually. I'm certain there's some small print in the contract to allow them to weasel out of repayment.
At $69.95 USD I couldn't afford to test it.
I just love some of these "testamonials":
"On average I would fill my tank every 3-4 days. Now I fill it once a week."
?My Toyota usually averages 233 miles per tank. Now that I've installed the Vortex Valve? I get 320 miles per tank. This is a 37% improvement in gas mileage."
"... it's fuel-efficient [increase of 13% in mileage on units in regular use], there's more horsepower [7 seconds 0 to 20 MPH] and lower emissions. I've actually driven behind another unit equipped with a Vortex Valve? and noticed that there was hardly any smoke coming from the tail pipe."
One thing I've always wondered...where did the people offering these testamonials find the product in question when it's relatively new on the market??? It's especially confusing when they say they've been using it for years yet no one else has heard of it...
I think you're right about this. I did read this somewhere before and I have heard that (in the case of the Swift-clone lineup) the Sprint and Firefly turbo models get better FE at high-speeds (110 km/h +) than their naturally aspirated cousins.
I would like to test this as well, but I know it will be a long time before I can get a hold of a turbo and exhaust manifold for the Metro.
EDIT: http://www.autozine.org/technical_sc...h_engine_3.htm Scroll partway down the page until you see "Light Pressure Turbo (LPT)". Looks like it could work. I'm not certain which vehicle year to look up on the EPA's website, though the 1993 Saab 9000 could be one of the EcoPower LPT motors.
Lastly, the efficiency of the turbocharger itself can have an impact on fuel efficiency. Using a small turbocharger will give good response and low lag at low to mid RPMs, but can choke the engine on the exhaust side and generate huge amounts of pumping-related heat on the intake side as RPMs rise