Is it?http://www.autoneato.com/peugeot-308-diesel-hybrid-can-it-compete-with-prius/

At 90 g/km of CO2, absolutely. If it were released today it would be the cleanest mass produced car in the world, since the current cleanest Prius emits 104 g/km of CO2.However, by the time it's released in 2010 there will also be several electric vehicles available, as well as the Chevy Volt and possibly the Prius plug-in (though I suspect the Prius plug-in will be a year or two later).Still, this is a great step forward for Peugeot. Diesel is more efficient than gasoline, and I've been wondering when somebody would come out with a diesel hybrid.

We won't know until the car actually is made. A number of cars never make it out of the concept phase, so are essentially vaporware.Currently, the lowest CO2 level for a diesel is the VW Polo Blue Motion, M5 transmission, 1.4 TDI 80PS (without A/C) with DPF, at 99 g/km CO2 levels. UK VED band A.http://www.vcacarfueldata.org.uk/search/vedSearch.asp(BTW: Toyota Prius and Honda Civic Hybrids are in the UK VED band B, so a little more CO2.)However, there are a lot more emissions than just CO2 to worry about (such as CO, NOx, HC, particulates - things that cause smog, acid rain, and asthma attacks), and diesel vehicles are usually worse than gasoline-powered vehicles in these regards...