The SAE has released free partial previews of some of the technical papers being published in conjunction with the annual SAE World Congress convention in April. Here's a list of the papers related to the 2016 Volt: GM 2016 Volt Overview The Next Generation “Voltec” Extended Range EV Propulsion System GM Volt Experimental HVAC Energy Efficiency Impact of Localized Cooling/Heating for Electric Vehicle GM Volt electric mileage statistics Chevrolet Volt Electric Utilization GM Volt 1.5L engine Development of the Combustion System for General Motors' High-Efficiency Range Extender Ecotec Small Gas Engine GM Volt power electronics Power Dense and Robust Traction Power Inverter for the Second-Generation Chevrolet Volt Extended-Range EV
"The addition of a high geometric CR and high-authority camshaft phasers for extended late intake valve closing (LIVC) operation has enabled improved low- and mid-load engine efficiency." Sounds like the ICE can go full Atkinson, and is more thermally efficient at high loads than the current 1.4L And, "Evaluation of one year of in-use operating data from first generation Chevrolet Volt Extended-Range Electric Vehicle (E-REV) retail customers determined trip initial Internal Combustion Engine (ICE) starts were reduced by 70% relative to conventional vehicles under the same driving conditions. These Volt drivers were able to travel 74% of their total miles in EV without requiring the ICE's support." So a little better than the two thirds figure usually used.
