For just $39.95, the Fuel Shark promises that you’ll get 10% better fuel economy, better emissions, more horsepower, and a longer battery life – just by plugging a little dongle into your car’s 12V power outlet. Having spent more than few years working with heavily intelligent people who spent hours, weeks, and months hacking into the ECUs of Mercedes and Porsches in a bid to just see what was going on in there – you might say that I was a little bit skeptical.

Still, one can be both skeptical and hopeful. So it was that this past Thanksgiving weekend, I plugged the Fuel Shark (provided by Fuel Shark, for the purposes of this review) into the Chevy Cruze diesel‘s outlet…

Fuel Shark Test

…and started off on the 330-ish mile drive home.

So, using the scientific method of “filling up the gas tank like, right at the start of the drive” and heading out along the identical route (careful I should add, to make stops that the same rest stops along the way), the Chevy Cruze’s on-board MPG calculator claimed 43.1 MPG on the return drive. This was a bit below what I saw on the drive out, which was Fuel Shark free. Weirdly, I showed a little over half a tank of gas left, compared to a little under half a tank on the drive out.

So – yeah. No matter how you slice those results, there was no 10% gain – which begs the question: is the Fuel Shark bulls***? I’m not ready to say it is, but I tried it again this past weekend in a 2014 Toyota Avalon and got similar “nothing” results. That said, I have a few uncles who are tough to shop for, and they eat this “As Seen on TV” s*** up, so maybe I’ll be a Fuel Shark customer, even if I’m not a believer.


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