Several automotive blogs -  Autoblog Green, Green Car Congress and GreenPowerTrain, below - have recently cited an announcement from battery maker PowerGenix:

PowerGenix unveils NiZn batteries for global micro-hybrid market

PowerGenix CEO Dan Squiller said micro-hybrids are about to become a fact of life in the auto industry and within four years, almost two out of five new cars sold globally will be micro-hybrids. ... The company said that the start-stop system improves fuel efficiency by up to 10% and is a cost-effective vehicle electrification technology, which is expected to be standard in Europe, with automakers in China and the US following quickly to adopt the technology on a mass scale.

That's great but what is a micro-hybrid? While a Full Hybrid has an alternate and separate powertrain that can propel a vehicle, a Mild Hybrid may only offer alternate power assistance at certain speeds, regenerative braking and a start-stop function. The Micro-Hybrid is just an ordinary internal combustion engine (ICE) vehicle with a start-stop system, and small electric motors to run AC and pumps instead of serpentine belts. 

What is a start-stop system? Instead of sitting in traffic, idling, wasting gas and exhausting fumes, a start-stop system will shut down the ICE when the vehicle is slowing or stopped and restart it upon acceleration. You could try that yourself, but it's supposed to be bad for the starter. Bosch estimates that start-stop systems can yield a five percent improvement in fuel efficiency, but since the EPA only includes one full stop in their city economy test, that efficiency barely shows up in their MPG ratings.

Start-stop, or idle-stop, systems were in use in a few European cars back in the 1980s and seem to have been slowly improving and gaining ground there ever since. Wired wrote about them as a solution to tighter Euro emission standards in 2006, and they seem very suited to small Euro diesels, and smaller cars in general. By 2008, Citroen/Peugeot was promising to make start-stop standard in their cars by 2010. In 2010, Lux Research said that micro-hybrids weren't sexy enough yet, but would dominate the US market by 2015.  In a recent article, another analyst, Frost & Sullivan, sees start-stop taking until 2020 to dominate Europe but moving slowly in the US.  

Gentlemen: Stop Your Engines

Because [Start-Stop] systems are relatively inexpensive and undeniably save gas and money, close to 100% of vehicles manufactured in Europe will have start-stop systems by 2020, according to industrial consulting firm Frost & Sullivan. But bringing wide-spread start-stop technology to all, or even most, cars to the U.S. has come at more of a glacial speed. Start-stop systems in the U.S. are used with hybrid vehicles (the electric motor in hybrids is used to restart the gasoline engine). The only conventionally powered (non-hybrid) vehicle to carry the technology now is the Porsche Panamera. ...

Strategy Analytics estimates that it costs an automaker between $162 and $333 per vehicle to add these systems. A full hybrid system, such as those in the Toyota Prius or Ford Fusion, which need heavy robust batteries to propel the whole vehicle at times, drive up cost to the consumer by $3,000 to $5,000, compared with non-hybrid vehicles. The cost differential for consumers of start-stop technology cars is much more digestible.

GM and Honda have already turned to less expensive Mild Hybrids for their Malibu, Civic and Insight hybrids, so it wouldn't surprise if manufacturers tried to satisfy consumer desire for greater fuel efficiency with start-stop systems on their smaller vehicles.