While I think it's likely OP will have to walk away, I think the approach and attitude laid out in A is much more likely to be productive, at least at the outset. +1.

@DavidRicherby I've edited the answer to preserve my advice while emphasizing the importance of doing this in a non-alienating way (what I originally meant by "courteous but clear"), and to modify the phrase that smci felt was self-aggrandizing. I doubt this will change many minds about the quality of this answer, but I do want to avoid the possibility of a misunderstanding.

I'm surprised at the reaction to this answer- I don't think I'm advocating trying to force anything or alienate people. My first suggestion is literally "just ask", and my second suggestion is very close to the two topvoted answers. You are all entitled to your opinions, but I stand by this answer- as I say, it's based on real experience, not just speculation.

+1 for actually answering OP's question rather than solely second-guessing their observations.

It's also worth noting that someone who never drives probably doesn't own a car, may not have a license, and may find even being a passenger terrifying or nauseating. Trying to categorize "legitimate" vs. "illegitimate" reasons is likely more complex than it seems, and should be avoided.

I suspect this is the advice I'll go with (+1), but see my clarification above. Can addressing likely skepticism or questions head-on ever be part of an effective "selling device"?

@DLS3141 the example I gave is just an example, but in my actual job search I'm applying for some positions that are very close to the subject matter I studied, and others which really are quite distant.

@skymningen see edit above; the intent wouldn't be to play myself down, but to use a particular pitching strategy. Though your advice is still good, and likely applies.