Should I continue spending money to fix my 2008 Mitsubishi Outlander XLS V6 Automatic 6 Speed 4WD?

If the rest of the car is good then you really just have two routine periodic consumable items (the belt and the exhaust) and two repairs one of which is likely to be very minor (the mirror switch: cheap and easy to replace if from a breakers yard). The window problem may or may not be an easy fix, but is nothing a competent DIY mechanic can’t fix fairly easily and still shouldn’t cost a fortune.

Leave the mirrors and the window alone for now and what’s left will admittedly be expensive, but they’re both likely to be a one-off expense which will cost less than a couple of monthly repayments on a new/newer car.

Your immediate priority right now is the timing belt. Gamble with that and the car could be worth scrap money only. You’d also waste a lot of money if you did the exhaust first and then suffer a broken timing belt.

buying pre owned is buying someone elses problems

At 123k miles, most vehicles, including yours, is near the 'point of no return', meaning that if you spend the money to fix it up now, with the expectation of some more repairs in the future, it's reasonable to expect another 123k miles out of it.

It's way cheaper to keep the Outlander than get a new one, and still a bargain considering a used vehicle, with unknown possible issues. At least you know what you've got now.

If it were mine, since I can fix almost anything myself, I'd fix & keep it, no question, but you wouldn't be here looking for suggestions, if you could fix your own car, so, do some research on some local shops and find a trusted mechanic who can give an accurate diagnoses and a fair price for the work.

Don't be afraid of small shops with just 1 or 2 mechanics or even someone working out of their own garage.

Good luck.

Since both mirrors are doing the same thing I would suspect the control button/switch. I would keep it and fix it. Easy stuff to do. But then I like paid off vehicles that start and run.

I look at this way, "Is it cheaper to fix her are replace her and I fix her is what end up doing for 100 BUCKS is cheaper than 20,000...

Is a replacement vehicle going to cost you more than fixing this?

You must take into consideration, trade in value, cost of new vehicle and cost of finance.

When it is cheaper the replace than fix then replace

What you describe above is mainly routine maintained stuff, the window probably just needs a smear of graphite grease in the runners, or even some washing up liquid, the mirrors could alswo be cold related.

Sell it. If you’re going to spend several thousand to fix it then it’s better to just save the money and use it on a down payment for another car. Once a problem shows up, more and more problems are going to start showing up.