Most of usclose to 92%, in factown a car. This country is so car-centric you have to do a lot of planning and investigation if you want to (or have to) try living without one. The good news is that modern cars are pretty durable in generaltodays cars have an average lifespan of more than 16 years and close to 160,000 miles, based on the cars that wind up in junkyards around the country. The bad news is that getting that much out of a car requires regular maintenance and repairsthe average cost of car ownership is now over $1,000 per month.Even with that maintenance, no car lasts foreverand there are usually signs that your car is about to go to that great junkyard in the sky. Some car problems are long-term, grinding issues that will have you limping from repair to repair for years, but eventually your car will develop a problem that indicates its going to have a catastrophic problem and stop running altogether. If you see any of the following red flags when driving your car, its time to start making a plan for a new one, because your current ride is about to die.You hear "rod knock"If you hear a loud knocking or smacking sound when you turn the car on, and it gets louder when you hit the accelerator, you might be suffering from rod knock. This can be caused by insufficient oil (from a persistent leak or skipped oil changes) or worn belts, leading to worn-out rod bearings. Sure, your car is still moving, but rod knock is a sign that your engine is about to close up shoppossibly in dramatic fashion. Repairing the problem can cost up to $3,500, depending on what the specific cause is and how bad its gotten.The car shakes and vibratesHas your car started to shake and vibrate every time you drive it? If you feel like youre on a bucking bronco every time you drive to the grocery store and your steering wheel is jerking under your hands, you should drive directly to the mechanic, because your car may be about to die. Violent shaking is usually a sign of an engine misfire or transmission problems. Engine misfire occurs when a cylinder in your engine isnt igniting the gas properly, and can be a significant repair depending on the precise cause. Transmission-related shaking could be caused by something as simple as low fluid levels, but could also indicate mechanical issues with the transmission itselfwhich might run you $5,000 or more. Either way, if your car feels like its going to shake itself to pieces when you drive it, its about to stop moving altogether.It's stalling when it shouldn't beIf youre driving a car with an automatic transmission, it shouldnt stall when you take your foot off the gas. If it does, it might not be a major problembut its definitely a sign that your car is gearing up to quit on you. The causes could be your alternator, which generates the electricity your engine uses to function, clogged filters, a failing fuel pump, corroded spark plugs, or even just a faulty sensor. Even if your car runs well otherwise, dont wait to get stalling checked out. You never know when youre going to stall at a traffic light and be unable to start the car again.The engine doesn't stop runningThe opposite of stalling is an overeager engine that keeps running even after you turn off the ignition. A running-on engine happens when fuel in the cylinders combusts on its own due to hot spots. Even if the engine eventually shuts down, its a sign of worse things to come because something is seriously wrong with the engine: Either you have malfunctioning or incorrect spark plugs, a damaged fuel injector, timing issues, or serious carbon build up in the cylindersthe latter of which is a pretty big problem if left unchecked, as it can lead to severe engine damage.The car's frame is rustedYou might think that a little rust on your car is no big dealand thats largely true if the rust is superficial. Even if rust has eaten away at your cars roof and it leaks when it rains, the car will still be drivable.But structural rust is a much bigger concern. When your cars frame starts to rust, its only a matter of time before your car gives out. Unless youre regularly under your car, however, you might not notice a rusting frame until its too late, but there are some warning signs that will tell you that your car is about to fail critically because of rust:Bending or cracking in the body. If any of your cars panels are warped, it might indicate your cars frame is weakened by rust.Stiff doors. If your cars doors are hard to open and close but your car has never suffered body damage (from an accident, for example), it might be a clue that rust is eating your vehicle.Holes. Have you looked under rugs on the floor recently? If theres a hole in your floor, your car has a serious rust problem.There's visible (or smellable) smokeVisible smoke of any kind coming out of your car is never a good sign, but certain smoke scenarios imply an emergency situation:Blue smoke. Smoke with a bluish tinge to it usually means oil is leaking into your engine and being combusted with the fuel. This is a very bad thing to happen to your car, and you need to get it checked out right away if you dont want to experience Total Car Failure firsthand. It might be a blown head gasket allowing oil to get into the cylinders. Failing head gaskets also let pressure backflow into the rest of the engine, causing even more problems.Sweet smoke. Is white smoke with a "sweet" smell to it pouring out of your car? A failing head gasket might be leaking antifreeze into the engine, where it mixes with the fuel. If your engine is also running hot, thats probably whats happening.If you suspect youve blown a head gasket, get it fixed right away. A blown head gasket can run you $3,000 or more to repair.Gears "slip" from one to anotherIf your automatic transmission starts grinding gears (shaking and making a lot of noise as it struggles to shift into the next gear) or starts slipping from one gear to another while youre driving, it might be a sign that your transmission is about to go boom. The fix might not be majorthe problem might be as minor as low transmission fluid, or a single worn-out part thats easily replaced. But it might be a sign that your transmission is cooked, and the worst way to discover that fact is when your car suddenly stops moving on the freeway.The headlights dim unexpectedlyIf youre driving at night and notice that your headlights are suddenly dimand getting dimmerit might indicate a failing alternator. The alternator generates the power for the headlights and other lights in your car, and if its not generating enough power those lights will dim and even turn off completely, even though the car continues to run. If thats happening to you, its only a matter of time before the alternator fails to generate enough power to run the car and it dies.Excessive and mysterious leakingThis one should be pretty obvious: If you notice a pool of leaked fluids under your car everywhere you park, youre on the clock to engine failure. If youre at the point where you have oil, antifreeze, and transmission fluid in the trunk and every trip begins with a top-off, you might have loose or failing gaskets or loose drain plugsand if those plugs or gaskets fail totally while youre driving, the results could be catastrophic if the engine loses all lubrication and fluid pressure suddenly.Your car is always telling you somethingand if that something is that its about to die, you should listen.