When writing stories sometimes author's will throw aside a little logical thinking to make their story work. I’ve heard this called the writer's handwave. It a way of saying, "I know it probably isn't possible, but it works." This is common in science fiction when writers will sometimes skirt the laws of fiction in how a ship will handle. For example, coming out of light speed would, in theory, send anyone not fastened into a seat by harness right through the bow of a ship. If a ship just suddenly stops when coming out of warp speed, like in Star Trek or Star Wars, everything inside that ship would continue to move forward at warp speed. Kind of like a car hitting a tree and sending its occupants right through the windshield if not strapped into their seats.
So, with this said, I suppose it would be a discretion to assume that Pete (Sleeping Through the Nightmare) could get any kind of motor running after sitting idle for a hundred+ years. To get around this, I put the story in the dry climate of a desert and vehicles within a garage where it would not be so subjected to the unforgiving environment of mother nature. As the series goes on, I added some believability in how Pete has to coat tires with roofing tar to seal them (The Gibbons' Seven), and how a pickup is started by a hand crank and runs on wooden tires as in (The Gibbons' Migration). This included one of the boys having to completely disassemble and reassemble a motor to get it started.
In the Gibbons' series, my goal was to keep the stories true to life in how someone would act when put into this apocalyptic environment. Pete has to learn as he goes, and he makes mistakes just like most people would. He will first think life is fun without rules but will learn all too soon that nature has its own rules that mean life or death.
I hope that I am accomplishing this by keeping my stories fun to read yet with a little balance of author discretion when needed. Thoughts?