Mazda's New Start-Stop Engine

We’ve heard about BMW’s non-hybrid start-stop engine used in the European 1 and 3 Series, but Mazda is developing a more efficient version. Mazda’s independently developed system, dubbed Smart Idle Stop System, should improve fuel economy by 10%, according to the company.

What makes Mazda’s system so unique is the way it restarts the powertrain. The system initiates engine restart by using its direct-injection system to squirt fuel and ignite it under the exact conditions needed to create the perfect downward force on the pistons, restarting the engine seamlessly. Mazda says drivers will feel no delay — it will take 0.35 seconds, to be exact — when resuming driving, just like in start-stop hybrid vehicles.

Mazda’s system is, arguably, much simpler than most start-stop systems, which are usually attached to hybrids, and it should weigh and cost less than GM’s mild hybrid system; that system is essentially an overblown start-stop system that improves gas mileage by 15% to 20%. Currently, most start-stop systems use an integrated starter-generator that combines regenerative braking and a battery to keep the alternator going when the engine is down. None of that would be needed here. Combine this technology with the new fuel-efficient turbo we told you about a few weeks back, and Mazda could boost efficiency by 40% in a few years without adding expensive hybrid technology.

SISS will launch on some Mazda vehicles in 2009, though we don’t yet know which ones, or if any of them are headed to the U.S.