I am building a 12V suitcase power backup. It can be charged from my homes power mains, my car, or a solar panel I have.
I thought it would be fun to be able to jump start my car if the battery is low, so I bought 12V worth of Maxwell supercapacitors. My research indicates that in their current state, they are not useful for storing energy, compared to the same volume of lithium cells. However, just about nany 12V battery can "fill them", and after that I am confident that the super-caps can easily start my 4-cylinder car.
The youtube video that convinced me disconnected the lead-acid battery from a car. He then disconnected the coil and fuel relay, so there was no spark or fuel. The fully-charged supercap bank turned over the 4-cylindercar engine for about 30 seconds. The recorded amps were 200A for half a second to get it rolling over, and roughly 100A continuous for the remaining 29-1/2 seconds.
If it was a diesel, a high compression performance car, or a 6-cylinder/8-cylinder...I'm sure it would draw more amps. Meaning, the supercaps would last even less time than 30-seconds.