Remember when gas prices spiked last year and everyone freaked out? Wasn't fun, was it? Driving suddenly meant keeping one eye on the fuel gauge and the other scanning the roadside for cheap gas stations. Automobile manufacturers took nearly a decade to meet the demands of America's growing automotive enthusiasm by releasing high-powered cars like the EVO, STI, GT-R and IS F, but mere months to flood the market with plans of fuel-sipping hybrids and tin-can-rivaling budget econoboxes once gas prices spiked. Not since the late '70s had "mpg" become a more important selling point than "hp", and even now that the crunch has passed (for the time being), those of us married to high-performance platforms look to increase both with equal importance.
Will This Product Increase MPG?
Fortunately (sarcasm alert), the dark corners of the aftermarket have saved the day, offering vegetable oil injection conversions, fuel line magnets, drop-in fuel tank artifacts, DIY hydrogen fuel cell kits, and liquid fuel additives, all in the nick of time. And we suddenly have our work cut out for us. This month we begin with the most suspicious example of the latter we could find on the shelves of our local auto parts store: Pro Blend's "More Mileage Plus", a fuel additive offering-among a short list of side benefits-up to 30 percent better fuel efficiency.
Our high-performance lab rat of choice was Subaru's '10 STI-a perfect candidate, considering its notably precise on-board fuel consumption computer, and that the only fault we found with the car was the 18.9 mpg fuel consumption we averaged while babying it to and from Buttonwillow Raceway for our STI vs. EVO Shootout (in an upcoming issue). Filling its tank with 91 octane pump gas, we set off on a 140-mile roadtrip from Long Beach, CA, to Oceanside, CA, and back, to establish a baseline, then added More Mileage Plus and repeated the test toward the end of the tank, to let the stuff work its magic. The route was selected for its mix of terrain and repeatability, and testing was conducted between 11 a.m. and 1 p.m. each day, limiting ambient temperature fluctuation and traffic congestion, to produce the most consistent parameters possible. Keeping pace with fellow motorists, speeds for each trip averaged right around 74 mph. The STI's SI drive was kept in "Intelligent" mode, with the differential set to "Auto"; air conditioning was left off, and windows were kept up for the duration of testing-slightly more civilized than how we drove it to and from Buttonwillow.
A 30-percent increase in our baseline fuel consumption of 22.7 mpg would've been good for 29.5 mpg. Reading over the bottle of More Mileage Plus, we discovered that this was only possible after adding one bottle to each of four consecutive full tanks; the first bottle should be good for a 10mpg increase, meaning our average should've been around 25.0. At 22.5, it wasn't. So, we added another bottle to another full tank of 91 and repeated the test, ending with an average of only 22.4.
|TRIP 1||70.5 MILES||22.8 MPG||78 DEGREES|
|TRIP 2||65.1 MILES||22.5 MPG||81 DEGREES|
|BASELINE AVG||22.7 MPG|
|TRIP 3||70.6 MILES||22.6 MPG||80 DEGREES|
|TRIP 4||67.2 MILES||22.4 MPG||81 DEGREES|
|FIRST BOTTLE AVG||22.5 MPG|
|TRIP 5||71.2 MILES||22.6 MPG||73 DEGREES|
|TRIP 6||66.3 MILES||22.2 MPG||75 DEGREES|
|SECOND BOTTLE AVG||22.4 MPG|
At this point, we weren't about to blow another $20 out the exhaust, and concluded that More Mileage Plus didn't do anything to elevate our STI's fuel efficiency. A list of ingredients or literature pertaining to how the product works couldn't be found on the product itself or its official website, but we did notice "fuel injector cleaning" benefits touted several times. Poor fuel consumption is more frequently a result of improper ignition timing or malfunctioning sensors than dirty fuel injectors, but we can't say definitively that older cars won't benefit from More Mileage Plus, not having tested any . . . just don't expect a refund if it doesn't work out that way.