Portable rechargeable battery (power supply) for tablets and phones that will also jumpstart large vehicle engines

Question

I am seeking recommendations for a portable rechargeable battery pack.

Requirements

1. Reliable
2. Can safely power tablets and phones (only need 2.1A at once)
3. Can reliably jumpstart a large vehicle engine (4.0L)

Preferences

1. As low of a price as possible
2. As small as possible

Bonus

1. Has a carrying case (but not willing to pay extra for one)

Note: Costco currently sells such a device for $59.99, but I have been unable to find any reviews of it, nor do I know anyone who has tried one.