Supercapacitors as car batteries

I've seen YouTube videos of supercapacitors replacing car batteries. Is this practical? And if so, why haven't they been offered in the automotive market place?

https://www.youtube.com/watch?v=GPJao1xLe7w

the type supercapacitor he is using has the following data sheet:

http://www.nooelec.com/files/2600f.pdf

Note that it contains 8,125 Joules of Stored Energy.

Then if you go to http://www.rapidtables.com/calc/electric/Joule_to_Watt_Calculator.htm and enter 8125 in the box and let's say 5 seconds of starting (it shd start up in 1 second in actuality). You then get 1,625 Watts. Remember 1 HP = 750 Watts , so you have just over 2 HP of starting power. Remember he's using six of them. 6 x 8125= 48,750 J. @ 16.2V.
(for a 2 sec. start it's over 24,000 Watts(32 HP) of instant power) Easily enough to start your car. Without a battery too.

A good car battery would have 700 CCA. @ 14V = 9800 Watts(13 HP). Quite a difference. (The average starter is 1.9 to 2 HP)

Here, as time goes by, I will post more videos to bolster my claim:

https://www.youtube.com/watch?v=EoWMF3VkI6U

http://www.extremetech.com/computing/183839-new-supercapacitor-technology-could-store-conduct-power-on-the-same-copper-wires

http://scitechdaily.com/graphene-based-supercapacitors-may-significantly-boost-power-electric-vehicles/

http://phys.org/news/2015-09-micro-supercapacitor-unmatched-energy-storage.html

https://www.tecategroup.com/ultracapacitors-supercapacitors/industry_news.php

http://www.skeletontech.com/news/skeleton-technologies-launches-markets-highest-energy-density-ultracapacitor/

https://www.youtube.com/watch?v=ZgozrScGN8U

Bottom line is, if you have enough Farads, you have energy density.

And this really settles the matter once and for all...

https://www.youtube.com/watch?v=JAT_8H23iGI