Tesla has shown that the demand for $80,000 to $110,000 all-electric cars is strong. GM has shown that the demand for $40,000 Chevrolet Volts is strong, selling thousands every month globally. Now the opportunity is there for Ford, GM, Toyota and others to fill that $40,000 to $80,000 space with large minivans and SUVs that have a 16 kW battery, large electric motor, and a 2 liter 4-cylinder range extender. The Ford C-Max Energi is a praiseworthy but very small step in this direction. Much more is needed. At the time of submitting this article, the author had no positions in the companies mentioned.Follow @antonwahlmanThis article is commentary by an independent contributor, separate from TheStreet's regular news coverage.