Will this work in our cars?

https://youtu.be/ADqk4IjzjXs

Yes, you will be limited to the capacity of the Spark’s converter for total draw. Off the top of my head I don’t know what that limit is.

Right, a 12 VDC to 120 VAC inverter will work with any car.
The Sparks DC to DC converter is rated at 100 or 120 Amps at 13.5VDC, can't remember which...

So conservatively good for ~1200 Watts 120VAC. This will power a vital appliances in the house.
It would be best to not push the max on any of these electronic converters in the train between your HV car battery and your home appliances.
Be aware of Sine Wave inverters for sensitive electronics versus the cheap Square Wave inverters.

Have a look at this thread in the volt forum for a "how to" with photos.
http://gm-volt.com/forum/showthread.php?303585-2016-Inverter-install-guide-with-photos&highlight=power+inverter

There is also someone selling the kits (more expensive), a Kit for the Volt gen 1 could easily be used for the spark.
http://www.evextend.com/

You don't really need a 'kit'.
Clamp or bolt on the inverter cables to the 12V battery under the hood and you have 120 VAC power.

Now to make this really efficient, you could get a 400 VDC to 120 VAC inverter and find a way to tap into the HV battery directly without wasting power having the car powered up.

The Chademo DCFC standard was supposed to offer Car to Grid someday.
Basically it allows 400VDC power to flow out of the HV pins at the DCFC charge port directly from the HV battery to a bigger inverter that would be synced to the grid.