This engine saves gas by shutting down most of its cylinders

The V8 Denali I'm about to drive isn't known for its fuel economy. But the huge GMC SUV isn't your usual over-sized grocery-getter. It's outfitted with Tula's engine optimizing Dynamic Skip Fire technology that reduces the amount of cylinders running at any moment to boost energy savings. So while all eight of them are firing when I take off from a stop light, once I'm at cruising speeds, the car settles into firing an average of two cylinders.

Reducing the amount of cylinders to save gas isn't new. What is new is how Tula is pulling it off. Current solutions reduce the cylinders by half. A V8 goes down to four. A V6 shuts down to three cylinders. The main reason for this is because of balance issues. If less than half are running consistently, the engine block would begin to whip back and forth. No one wants to drive a car with an engine that's about to rip itself out of the vehicle.

Tula's Dynamic Skip Fire technology works on the same principle, but instead of using pre-determined cylinders, the company's control unit dynamically selects which ones to fire at any moment based on the needs of driving situation. So instead of just shutting down half the cylinders, it can shut down seven of the eight at any one time by moving the firing cylinder around the engine therefore stifling the balance issue.

While driving the Denali the fuel savings averaged about 18 percent using the Tula technology with Delphi hardware. Delphi is an investor in the company but the system will work with components from other manufacturers and is expected to be in production vehicles by 2020. The company is already working on a four cylinder version and while the results may not be as dramatic as the V8, if coupled with a plug-in hybrid get ready for another boost to the fuel efficiency of cars.