Omi is the opposite end of the spectrum. He's a good example of what would make the "Acting Sheriff" just as suspicious as him driving what he is.
She's gonna be thinking, "Hmmm, one of these things is not like the other."
Is an 05 Lexus gonna raise any eyebrows? Is that TOO flashy or does it more closely match what Wendy is driving?
The daughter's Mystery Mobile is probably appropriate in some sense, in order to blend in with the local yokels (to get high in and fuck, etc.) and the bratty son is still riding bikes.
I'm not wondering why Marty isn't pushing a Bentley or anything but it doesn't make any sense to push an eyebrow raising POS whooptie either. That Lexus would fit his white collar profile just as suitably for remaining under the radar. That's ALL I'm saying.