CO₂ reduction targets are a big challenge for the mobility sector because about 20% of all CO₂ emissions originate from road traffic. The problem is intensified by the expected traffic growth which will mainly take place in developing countries. Several powertrain and fuel technologies are competing regarding their CO₂ reduction potential compared to conventional gasoline and diesel vehicles. Hybrid electric vehicles with a certain energy saving potential as well as natural gas vehicles (NGVs) with their lower fuel carbon content are expected to gain on importance. But why not combine dedicated natural gas engine and hybrid powertrain technology to achieve very low CO₂ emissions even for mid-size passenger cars? At a first glance, such a powertrain combination looks just like a combination of two expensive technologies without any market potential. A more detailed analysis shows, however, that NGV hybrids allow high CO₂ reductions without additional end-user costs over the vehicle's entire lifetime. The present study addresses both topics: it presents the CO₂ reduction potential of mid-size passenger cars driven with an average natural gas-hybrid powertrain and it addresses end-user costs compared with today's gasoline technology.