Stop-start systems, which have been used in hybrid vehicles for almost 20 years, are now becoming common features on non-hybrid vehicles as well.
According to the DOE, the market penetration of stop-start systems in non-hybrid passenger cars grew from 9.1% in 2016 to 14.2% in 2017, while their use in light trucks nearly doubled, reaching 20.3%.
Stop-start systems are particularly effective in city driving where brief but frequent stops are required. According to the EPA, they improve fuel economy by 4-5%. Engines with stop-start technology have several differences from conventional ICEs in order to prevent premature wear of engine components, including the starter.
Source: DOE via Green Car Congress