About fuel economy as the primary reason the demand curve has dipped. In any case, the supply side is just too saturated and continues to depress prices.
I hold a large short position in oil right now and I can tell you that none of the traders are talking about clean energy as an immediate threat to oil prices. Were talking supply builds/draws, rig counts, etc.
Clean tech will have it's day but not right now. If it is having an effect on oil prices it's an afterthought compared to supply.