Fitted with a 329bhp 3.0-litre V6 turbocharged engine, which is paired with an 80-kW electric motor, the S500 hybrid will return 94.2mpg and emit only 69g/km of CO2. It is also capable of covering up to 18 miles purely on electric power alone.
The link above is a graph of the trend in emissions from 2005 and forecasted to 2025. The trend across the sampling is down, and in some cases rather significantly. Though these were also higher start with. Notably, the M-B above would not even register on this graph. It appears that the continued advancement in clean technologies are valuable efforts in improving emissions.