Revolution is a post-apocalyptic TV series, where the main premise is that some sort of technology was used to disable electricity (as in not just the mains but electricity even in batteries doesn't work).
As far as I know not all diesel engines have glowplugs and those that do can be started if they are not functioning, not to mention that from what I understand, the function of a glowplug could be replicated by heating the car (ie putting it near a fire). In addition diesel engines can be run on straight vegetable oil, which seems pretty useful in a world where fuel pumps no longer work and farming has become common place. And horses (horses are very abundant in the Revolution universe) could be used to roll start larger diesel vehicles.
So why are there no cars at all? Not only that but they go so far as to get a steam train running (note that the tracks had not been used for many years so it's not just locating, moving and servicing a train, it's also servicing the tracks), a seemingly more complex task than roll starting a diesel engine with non functioning glowplugs.
Is there something I'm not getting about real world or in-universe physics here?
Edit: I was referring to older model cars which do not use computer/electricity for any of the necessary functions (eg fuel injection). I would like to add to that any homemade device which makes use of a diesel engine, for example a home-made vehicle or a home-made water pump.