so are we trying to move ourselves, or stuff?
I will stick with the Bike as the best self mover- at least if leaving from home. 
20.00 for a used mountain bike at goodwill- cheap, available parts, tough, mobile, and fast.   Even if you are out of shape, as long as there is flat ground, you will move farther. 
But....
I am at home 10 hours of a 24 hour day.  I don't have room in my 12 yr old Subaru Forrester for a bike, even a folding one....
I have not settled on a model for my car, but I have experimented with a kick/razor scooter. My kids have several folding models that weigh under a pound. Even without practice I still went 5 MPH for about 1/2 a mile, and was not out of breath. I know I can do it with a small backpack. 
I am intrigued by this site-   
http://www.cambiecycles.com/scooters.html   adult sized scooters- under 200.00  Not sure if would fit in a car.  
I think I would argue that moving people faster is in "most" cases going to take precedence over more stuff slower. Me plus bike plus 30 pound pack= 10+ MPH.  that gets me from Omaha to Minneapolis in 4-5 days, assuming 8 hours travel. I am 43, and in average condition.  Your solar powered scooter will pass me on day 1, but unless you can find a way to recharge, I will get there first.  I suspect that the bike pulling the stroller would be harder, but still, the mechanical advantage is hard to overstate...
I am willing to be wrong-  maybe your bug-out is only 5 miles away, and not stocked;