Value vs. Worth (how my car started me thinking)

I'm going to go off topic here and talk about what things are worth to me.

This whole topic was prompted by my automobile.  My car is nine years old now and it runs well enough but it's started to have problems and they are adding up.  I'll start with an annoying little problem this model is prone to, an engine check light because some doo dad is out of spec.  I had the specialists pull the engine codes and they explained what it was.  It had to do with some moving parts in the accelerator that rotate and control my current speed when I press or release the gas.  It want's to be replaced for about $700.00.  The engine runs fine, the gas mileage is above par for the make and I have better things to do with my money.  So I live with a constantly burning engine check light.  Last year during a sever freeze, my driver window broke. More precisely, the arms that make it go up and down bent.  Replacing them would have been $600.00.  My mechanics kindly locked the window in the up position and I don't do drive thru windows when I can avoid them.  Somewhere along the line, the air dam broke and fell off.  The car runs fine.  The plastic cover over one of the fog lights broke.  The lamp still works, but it's unprotected.  One of my wheels cracked while I was out of town (900 miles out of town).  Replacing all four wheels, $550.00.  I replaced one, but now the tire people don't want to rotate my tires because the wheels don't match.  A couple weeks ago, the blowers in my AC went out.  I can still feel the AC kick on and there is cold air at the vents.  It just can't blow it out.

So, to get my car back into optimum condition will cost me at least $2,000.00 and I'm not including the new set of tires that are due real soon.

According to Kelley Blue Book (www.kbb.com) my trade in value is only about $2,000 to $3,000 ($4,000 if I sell it myself.)  So I wonder if it is worth fixing or better to replace?

I'd love to get a new car, but this car runs well and it's probably worth more than $4,000 to me.  It's paid for and any new car would be at least $300 per month.  Maybe if the government gives us back interest deductions on cars, the value of a new car will look better to me.

So I must consider how much a new car will cost, at least $21,000 I think (plus interest), vs. $3,000 to fix this one up (and another grand for what comes next.)  Will any new car give me $15,000 additional value in terms of use?  Probably not.  Unless they offer us a hybrid with long lasting magical batteries, or a combustion engine that runs on water, I don't see the extra value.

Thanks for hearing me out, have a nice day.