The motor blew out on my husbands car a couple days ago. We didn't owe any money on it and it did have 140,000 miles on it but we expected it to last longer. We do try to follow Dave Ramey's plan. We owe money on my van for another 2 2-1/2 years. If we put a new motor in it will be around $3500-$4000 plus car rental for 4 weeks. We think that's too long to borrow a car on. Plus we have checked around everywhere for a used Toyota (my husband works for Toyota so we feel like that's what we need to get) and there are no used Toyotas in the price range we want. I told him I don't want to go longer than a 3 year loan and not strap us so what we came up with was $8000. We don't know what to do. I would love to just go get what we want, get a 5 year loan and not worry about it but that's definatley blowing Dave Ramsey out of the water. If we put a new motor in we could pay cash for it but it would completely drain our emergency fund. Okay, I'm done venting for now...
I don't think that I would sink 4K into an old car. I would try to find something else. I wish you the best of luck. 
Dad says those guys usually come to work with a new Ford vehicle within a month. Thankfully, my Dad doesn't get involved with such things, he doesn't care what the guys drive, so long as they show up to work.