Using Lean Burn Mode to Get 37mpg in a Tuned C5 Corvette

YouTuber LegitStreetCars wants Prius highway mileage while cruising in a C5 Corvette and still enjoying 364hp at the wheels!

Alex Palmeri, better known as LegitStreetCars, is one of our favorite automotive YouTubers. He’s a former Mercedes Master Tech who produces some of the most informative how-to auto videos on the Internet. He started his channel with a 1,000 horsepower Trans Am. Then moved on to various Mercedes AMG and BMW M cars. Most recently, he’s been restoring a 1999 Corvette C5. He’s a smart dude who makes complex issues easy to understand.

Where most of his projects aim to add power, Alex dubbed his C5 build the “Eco Vette.” His goal? Obtain Toyota Prius-esque gas mileage on the highway without sacrificing any of his LS1’s V8 grunt and roar. In fact, Alex not only wants 40mpg, but he also wants to boost his C5 to 2001 Z06 performance (which featured the LS6).

Enter Lean Burn Mode

For the above video, Alex took his C5 to Mike Hornback at Hac Tuning, where Mike first established a baseline using a Mustang Dyno. He then boosted rear-wheel horsepower from 349 to 364. Lastly, Mike used Lean Burn Mode to tune Alex’s Vette for gas mileage. But what is Lean Burn Mode?

Pardon the over-simplification, but here are the basics. Most factory tunes want your car’s air-fuel ratio (AFR) to be a 14. Not too lean; not too rich. A lean tune will toast your engine, where a rich one will gunk it (and your cats) up. Lean Burn Mode is a special kind of tune that allows you to run extra lean in conditions where it won’t damage your engine. The idea is to reduce fuel consumption, which improves gas mileage.

To make Alex’s C5 run in Lean Burn Mode, Mike edited the Corvette’s tune. Specifically, Mike told Alex’s C5 to run Lean Burn Mode only when the Corvette was in 6th Gear and driving 60mph. In other words, when rowing gears 1-5, or when driving in 6th gear at other speeds, the Corvette stays tuned for performance. But in 6th gear at 60mph, the C5 sips gas with economy in mind.

Talk about having your cake and eating it too.

After finishing the tune session at Hac Tuning, Alex drove his C5 home about 40 miles where he averaged 37mpg despite two-plus miles of city driving and getting stuck in Chicago stop-n-go traffic on the highway. Color us impressed.

What about you, dear reader? Have you ever experimented with Lean Burn Mode? What’s the best mileage you’ve ever gotten from your Corvette? Or are you more about smiles per gallon? Let us know in the comments below!

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