The car industry has alreeady woken up.
The Peugoet group is installing capacitors in their stop/start Valeo system using Maxwell capacitors, so CAP-XX will have to start from behind:
http://www.greencarcongress.com/2012/02/valeo-20120228.html

Other car companies source from Peugeot.

Unfortunately the market leader, Johnson Controls, simply uses an AGM battery, and so personally I would not specify stop start for cars which use them, as replacing the battery is likely to be expensive.
VW for instance uses them in their Bluemotion cars.
Avoid them.

It is marketing, if people are not interested then NO sale. Some in Europe may be interested in start/stop but not in the U.S. In America, the only time they want it to stop is when they turn the key off in the garage.

@Harvey
?? It is supplementary as the article clearly says.

Seems like you could also then downsize the lead-acid battery and save weight overall, too.

Sounds all good to me--small, cheap & saves money in both the short run and long run. Idle-stop is the lowest of the low-hanging fruit for reducing fuel consumption (apart from using your bicycle more and car less). Anything that speeds adoption of idle-stop is a good thing, IMHO.

DaveR you win the internets today. That's a great perspective: it's not the cost of buying a Li-ion (or NiMh) battery, it's the cost of saving an equivalent amount of weight via another method, such as switching the hood and trunk lid to aluminum. That's especially true when you consider the design, sourcing, tooling, fabrication and testing load that attaches to changing body parts, as opposed to simply switching out one battery box for another. Great point.

So I can get 10 pounds out by adding $100 to the cost. Now the car gets .01 mpg better and costs $300 more. I don't think that would sell in most car company marketing departments.

If the idea is to use caps for starting, then use a smaller lead acid battery to save weight, it sounds like a "solution" in search of a problem.

I suppose a case could be made for such and arrangement, I just don't see many car companies going for it...but that is just MO.

Getting rid of non-essential weight such as spare wheel-tire, heavy lead battery, heavy steel wheels, ICE, metal radiator, heavy inefficient A/C, transmission, heavy drive shafts, steel brakes, heavy steel frame and body, doors etc is the way to 2X+ current efficiency for our personal cars while maintaining the same inside cab size.

A 1000/1500 lbs HEV, PHEV or BEV would require a lot less batteries than the current 4000 lbs units and would cost a lot less to build and to operate.

Common sense will eventually prevail but buyers will have to go through an attitude change first and accept that lighter and more efficient is better instead of bigger and heavier is better.

SJC....during the last 24 years, our average car and small truck fleet has gone from 22 mpg to only 22.6 mpg because our manufacturers have built heavier and heavier vehicles, from about 2800 lbs to over 4000 lbs. All the gains from more efficient ICE, transmissions, tires, etc went up in smoke.

During the same 24 years or so, our Junk Food industries have also been very successful . We went form less than 20% to over 40% obese.

In a way, bigger-fatter (300+ lbs) drivers and passengers seem to justify heavier vehicles. If so, both problems may have to be fixed. otherwise, we may seriously need to revive the 8000 lbs Hummer I.

SJC....Some 100 years ago a 5-passenger Ford Model T had a 100 inch wheel base, a 120 cu. ft. cab, weighted about 1200 lbs, sold for less than $500 ($260 in 1922) and could drive off roads with its very large diameter wheels. Many farmers used it as an early tractor.

A similar car today weights almost 4000 lbs, cost $30K+, carries the same 5 passengers on roughly the same 21 mpg. All the gain in ICE efficiency went to propel the added weight. A 1200 lbs, 5 passenger car could probably do 80 mpg or about 4 times as well as a Ford Model T.

“Additionally, the supercapacitor module will start the engine in low temperatures (cold cranking) where a battery would falter, and can store energy in vehicles with regenerative braking systems (also known as Kinetic Energy Recovery Systems or KERS).”

Well, the cold cranking has some value but the module’s contribution to regenerative braking would be rather minor, but not insignificant at lower speeds, since its amount of energy storage is about 4 Wh [ ½ (150) x 14^2 /3600]. The kinetic energy in a 3,000 lb. car traveling at 60 mph is about 150 Wh; and, at 30 mph, about 16 Wh.

So, at $60 per module ($15,000 per kWh), regenerative braking would not be the raison d’ȇtre for supercaps. However, if the module is already available, then use it so long as the cost of its integration is less than $2.00, $500 per kWh, or whatever the battery cost is.