Easy as A123? Maybe not so much.

David Vieau, the CEO of A123 Systems, recently testified before the US Senate Committee on Finance abut the future of advanced vehicles. A significant part of his testimony focused on a recent decision to partner with Hymotion to to develop and sell range extension conversion kits to owners of existing hybrid vehicles.

Now, the folks at A123 are smart folks (I've said as much previously). Far be it from me to critique a bunch of MIT professors and the like; engaging them in a battle of wits would be like sending me into a knife fight with a feather duster.

But with all the major car makers racing to be the first to produce PHEVs (with A123 supplying the battery technology to GM), my sense is that the crop of after market conversion suppliers will shortly be irrelevant.

Vieau points to the fact that there are will be 1 million HEVs on the road by the end of the year, and perhaps 5 million by 2010. OK, that's a lot of cars.

But at a cost of $10,000 (less a purported $3,500 tax credit), the average consumer is going to balk at the cost. Furthermore, manufacturers will almost certainly be close to launching their own PHEVs by 2010. It's reasonable to expect, I think, that a significant portion of hybrid owners will be more interested in upgrading to a new PHEV versus converting their old HEV.

Is there a market for after market conversion? The numbers on the surface seem compelling. But I'd be surprised if 1% of those projected 5 million actually pursued conversion.