When do you stop putting money into your vehicle to fix and upgrade it?

I think it depends on if you can do any/all of the work necessary yourself when it comes to repairs.

If you must rely on a shop to do any/all necessary repairs, I'd say it makes little sense to pay for any repair that's much greater than the book value of the vehicle after the repair is complete. I say that because if someone were to crash into the car after the repair (even by no fault of your own), THEIR insurance isn't going to compensate you for any recent repairs - all they legally have to do is give you the book value of the vehicle at that point. If the book value is less than the cost of the repair, you'll be eating the cost of the repair yourself and on a car you'll no longer be able to drive. That's no good.

If you CAN do some/all of the labor necessary to conduct a repair, then I'd say keep repairing the car until something major fails (I personally draw the line at an engine/trans failure for example, where even the part cost alone is going to be more than the value of an older vehicle). Even if the book value is low, if you can do the work yourself on a less-than-catastrophic repair, then the cost of parts alone probably isn't going to cost more than the vehicle's book value.

As for upgrades, I treat upgrades solely as money I'll never get back. Kind of like buying a cup of coffee... if I'm okay spending money on a cup of coffee because I think it'll make my day better, I don't sweat that I'll never see that money again. Insurance companies generally won't compensate you for added upgrades so if the car is wrecked (again even if it's not your fault) you likely won't get paid back for the upgrades you've done, so I wouldn't sink $1000s in upgrades for that reason. You're better off just buying a better (and more valuable) car if you'd rather have something nicer than to take a low-value car and sink $1000s into trying to make it "better".

as USUAL< Dr. BEAR FACE< is WAY off track and makes me ANGRY! Hsi answers are JUVENIL Enad not based on ANY reality!>> when you buy a BMW, AUDi or BENZ< you get a THRITY YEAR CAR! They are SAFETY CELL engineered and usualy wil NEVER have any rusting! Since I have been restoring cars for YEARS< one way or the other, I woudl say that if the FRAME and SUBFRAME are STILL rust free, GO AHEAD and keep it going! WE should have EXMAINATINO stations for SAFETY SAKE< in every major city providing JOBS and keeping the roads SAFE and free from accidents and INJECURIES! The CARS shoudl bne made SAFE in the first palce, and THEN add in AIR BAGS and SEAT BELTS if the cr tests out OLAY!. I STIL cannot fully comprehend WHY a person would buy a CAMARO< when you cannot even SEE out the windows! ANY CAR has a REPUTATION! MOST people AGREE that a TOYOTA is made VERY WELL and is GREAT with fuel and VERY safe! I AGREE here as well! I have restored MANY AUDI and BMW cars over the years and I would trust a TWENTY YEAR OLD audi or BMW or BENZ over a NEW GM car of ANY type! The AUDI A8 is made from 100% AMERICAN ALCOA aluminum and is UNGODLY quick and long lasting! Even a USED ONE has features noon would assume! SADLY most AMERICAN cars and trucks STILL have LONGEVITY issues! I repair shop near me stays ALIVE by replacing the BRAKE LINES and HOSES in GM cars that are about 8 years old! The EUROPEANS put the BRAKE LINES inside the cars to PROTECT THEM from corrosion and use BETTER MATERIALS in them! IT is NOT funny to me that we STILL do not make cars that can COMPETE with REAL car makers, like AUDI, BMW, and BENZ or even SAAB or VOLVO! Expect for FORD, that owned ASTON MAR$TIN< JAGUAR and VOLVO for a while and uses THAT technology in nearly EVERY vehicle they make! PERSONALLY I have restored MANY EUROPEAN models but have had them STOLEN before i could collect ont he improvements I made!. I TRUST European cars ther MOST, and FORD now is mostly EUROPEAN! They use the SAME suppliers that AUDI , BMW and BENZ have uwd for decades! ANd ZF company RULES with the best TRANSMISSIONS out there! WISH I had STOCK in them, and Bosch as well!. SADLY for YEARS< GM has made cars NOBODY WANTED TO BUY! THey NEVER tested them thoroughly enough an many peopl LOST their LIVES or PETS or gotten BAD injuries in them! SO MAY GM models could NOT pass simple CRASH TESTS! NOw they are MUCH better but I stil MISTRUST THEM totally!. a MUSTANG is great to update if it was made after 1995 usually! I have said that the ERUIOPEAN cars are made for EASE of reapir, and that DOMESTIC cars are made for EASe of ASSEMBLY! The HOOD on a BENZ< e.g, can go FULLY VERTICLE for ease of working on! THe CHOICE of MATERIALS is VITAL for longevity here! BYE for NOW!

A huge factor is your own personal financial situation. All but the most expensive repairs are less than the price of a reliable used car. You might have money for one, but not the other. That's the situation I'm in now.

When repair costs exceed replacement cost adjusted for reliability.

For example, my 1986 Camry just took $1,100 to repair/fix up. It had 116,000 miles at the time and is more or less rust free.

To replace it with a reliable, low mile, rust free vehicle in my area (w/manual transmission and good mileage), I am looking at close to $10,000.

I plan on doing at least 125,000 more miles on it with a budget of a couple hundred a year for oil/tires/maintenance. As long as I stay on top of it, it will likely go well beyond that. So the initial $1,100 to get it up to snuff makes sense to me. Most people would have likely sold it for peanuts.

Have friends that have dumped cars that were amazing, but needed a couple hundred dollars of work for peanuts, just to buy another used vehicle that required more or less the exact same work a year later, and keep on repeating this cycle. Not realizing that losing $3,000 a year is a lot more than ~$500/year to keep a vehicle in tip-top shape.

If repair costs exceed the value of the car in a years time, it's time to get another car. However, it's not only about the cost of repairs, it's also about the inconvenience of breakdowns, time lost, loss of use of vehicle while it's being repaired, the aggravation, and the the fact that you cannot fully depend on the vehicle anymore.

When you have listened three times to the stories of your mechanic about his days as a machinist mate on the USS Ticonderoga.

HI ten years old would be a good marker.

When the cost of repairs cost are more than the vehicle is realistically worth.

It doesn't make sense to me to put $2000 into a vehicle which I can only get $1000 if I were to sell it in good condition for example.

Most issues come from trying to save money and short cutting mistakes.