Sorry for the length of this, but at least you’ll get a few laughs off me. We own these three cars, and currently only one is drivable. This is sort of a general ‘what would you do?’ opinion question on where to go from here. If it’s too long to read through, I completely understand- but thanks to anyone who does and gives advice! Here’s what’s going on with each car:
Car #1- 2005 Pontiac Grand Am:
The good: It’s in great shape inside and out, no accidents, and it runs well.
The bad: The heat sometimes smells of gas if the car isn’t moving; it has 59,100 miles (daily highway commute); we owe another $10k-ish on it; and I’m betting the transmission could do with a flush (recommended to us about 6 months ago).
She actually tried to trade this in on a 2007 Chevy Impala- which we drove it for a week, then the dealership couldn’t manage the financing they promised. Made her very sad, she completely loved that Impala. But the 13% APR, $7500 trade-in value, and $20k+ loan for a used '07 Impala they offered? No thanks.
Car #2- 1985 Buick LeSabre LTD (Collector’s Edition sedan).
The good: This one’s my beast. I love the big old built-like-a-tank cars. Picked this single-owner up for cheap out in southern California, drove it home to Utah.
The bad: This will start sounding like a theme here, but I’m an idiot- the car’s great, but being from So. CA, they were using more water than antifreeze in it. Winter hit, and the radiator froze/cracked. I was quoted $380+ to fix it at the local shop. The radiator itself is $123+ tax for a new replacement, if I put it in myself (closest car yard with a cheaper used one is 90+ miles away).
Well, I refuse to spend $380. I’m not a mechanic, but I have replaced a radiator before. Problem is, that was leisurly during summertime on pavement, not hurriedly in snowy 15F chill. I’ve got nowhere to work on the car- it’s outside in the non-covered driveway. My wife and I work over 30 miles apart at the same time; we REALLY need two cars. So I thought I’d be clever (ALWAYS a mistake!). Enter the next vehicle…
Car #3- 1994 Ford Taurus.
The good: I bought this locally for $375 last week intending to use it as a cheap commuter car until the weather warmed up. I work only 4 miles away so don’t need anything fancy, and figured I could easily sell it off at a profit once I fix my Buick. It looked in good shape, ran nice, and had tons of new parts. It came with an impressive $4,000+ worth of receipts for the past two years (not counting routine maintenance). It had passed safety & emissions 3 months ago, and had all power features, redone AC- even a moon roof. It looked like it would be a great commuter car, and would easily fetch $500 or so when I went to get rid of it.
The bad: I got duped. Turns out the guy knew it had a blown head gasket, apparently par for the course with this year/model. Keep in mind I’ve never owned a Ford. He was clever though. Just before I arrived, he emptied and replaced both the oil and coolant. When I checked them, they looked full and clean. The car ran nice, had impressive service records, and it passed my standard tests. I was an idiot. It got 3/4 of the way home before it overheated and began burning antifreeze. With constant stops to cool off, I got it home and parked it; another testiment to my being an idiot.
So that’s where we are. My wife still really wants an '07 Impala. If we sold the Pontiac, we can get excellent financing through her credit union… but $10k+ (our payoff) is a bit much to ask for it with the high miles. I listed it locally anyway, but unsurprisingly got few bites and no offers. And because of my stupidity, I still need a car. This week I guess I’ll purchase the $123 radiator for the Buick and try to install it myself in the snow (looks nasty out there, but what choice have I got?). I’ll still be stuck with a $375 lemon that looks good, moves, but according to everything I’ve read isn’t worth its weight in scrap metal. So does anyone see a way out of this mess that convinces my wife I’m worth keeping? 
Thus far I’m 0/3, and obviously my ideas are worthless.
The Grand Am has a problem with its evaporative emission system, and I’m willing to bet that you could get it fixed for free at your Pontiac dealer, as emissions parts tend to be warranteed long beyond the rest of the car. You’re never in your wildest dreams going to get 10k for that car. Maybe 7 or even 8 if it’s in great shape and the potential buyer doesn’t stop for too long and become asphyxiated by gas fumes.
The LeSabre. You’re being a cheap skate. For 5 dollars more than the cost of the Taurus you could be driving your nice old Buick, rolling through the snow with the heat up full blast and the tunes blaring.
The Taurus. Remove the plates, pop off the vin tag, leave it by the side of the road. 
Good luck with it all, man. The first two are easy and way cheaper than buying a new car.
I agree fix the first 2 cars. Seems early for the trans flush. isn’t it supposed to be at 100,000 miles?
Fix and drive car #1, there is no point in selling a car with an upside-down loan. Keep it long enough to get some positive equity, at least. This thing is costing you a few $100 per month in payments, so use it and keep it in decent shape. I would plan on driving it well past the end of the loan to get a little ahead on your car budget.
Fix and drive car #2, either do it yourself or pay to have it done. I don’t understand the logic of buying a $375 car (#3) to avoid a $380 repair on car #2, but what’s done is done. Just get car #2 back on the road, even if you have to pay to have it fixed. Keep it in decent shape and plan on keeping it as long as it’s reliable transportation.
Dump car #3. you can try to get your money back from the seller, or try to sell it as a parts/project car on ebay, or just call the junkyard. Either way, you don’t have much invested so don’t make it any worse. just get rid of it and write it off as a “learning experience.”
No offense, but why are you looking at a 2007 car with another upside down loan? Even if you qualify for a decent interest rate, you are looking at doubling your car payments. Take that extra money and use it to get you two existing cars in reasonable condition, then drive them until your car payments are gone and you have enough cash for a very healthy down payment (at a minimum).
I agree with Craig on all points. The only thing idiotic I see here would be making yourself even more upside down financially by buying an '07 Impala.
(In regard to the gas smell, you might closely inspect the fuel rail and injectors to see if an O-ring is leaking or you have a cracked injector body. That can be a serious fire hazard issue.)
Have to agree that doing anything to the Taurus is sending good money after bad. In cowboy country they would say: “Shoot it in the head”. Buick LeSabres tend to run forever if treated right. Nurse that one.