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Why are certain cars more reliable than others?

I see here posts of all sorts of ways cars can break, causing the owners no end to the grief. But some cars seem ot have fewer problems. Or they might still have about the same number of problems, but they are less expensive to fix problems. On one car if it overheats, it needs a new thermostat. On another, it overheats, it needs a new head gasket. So I’m wondering why some makes/models seem to be more reliable than others.

Is it the basic materials used that determine of the longitivity of the car? Do the more reliable cars simply use more durable materials?

Or is it more the overall design of the car and the way the parts work together? Do the more reliable cars have a more robust design, making them more fail-safe?

Or is it that the more reliable makes/models go through a more thorough testing process before they are sold to the consumer?

Or is it that the more reliable cars are simply easier to do the routine maintenance and easier to diagnose and fix?


Just curious what the mechanics who work on cars on a daily basis out there think. Any examples of failure modes in unreliable cars that turned out to be more expensive than necessary to diagnose and/or repair because of an inadequate design? For reliable cars, any examples of a failure that was inexpensive to diagnose and repair because of the way the car was designed?

@GeorgeSanJose

There’s no one answer for your questions

I will say that some of the more unreliable brands claim to go through rigorous testing before offering them for sale.

Some expensive technology is trouble-prone.

Some cheap technology is very reliable.

Many unreliable cars are relatively easy to diagnose.

Many unreliable cars are even relatively easy to work on.

Thermostats are one of the most common failures on all cars. While they often get stuck open, causing massive delays in reaching operating temperature, I’ve also seen them fail in the stuck closed postion, causing overheating.

Plastic radiator tanks often crack after years of service. Yet cheap and expensive, reliable and unreliable cars all use them nowadays.

@Georgesanjose Yes its all of thsoe. I teach workshops in reliability engineering. It simply goes: 1) Design it right, 2) get the right quality into the parts by Six Sigma, 3) assemble it right, and 4) provide the right maintenance procedures and practices.

Japanese companies learned this the hard way, but by the late 80s they had mastered most of it. Designs have to be fit for purpose for local conditions. That’s why European cars did so miserably here; the makers could not care less about the guy in Minnesota or Alaska, or in Arizona.

Nissan’s initial; cars were dismal. They withdrew all of them and started from scratch. They had a Japanese designer live with a California family for a year to learn what Americans actually do with their cars.

The biggest contribution was statistical quality control and the Six Sigma which only allowed one bad part in 340,000 or so. Up till then GM tolerated 5% bad parts which were built into the cars and the warranty was supposed to cover that. Assembly defects are down to less than 2 per hundred vehicles in Japanese plants. By contrast the reject rate at the infamous British Lucas facilities was 30%!!! in the 60s and 70s.

While GM, Ford and Chrysler were constantly trying to cheapen cars by lowering component quality, Japanese companies were doing the opposite, built the best parts at the lowest price. The Toyota Production System book makes good reading.

So, design it right for the intended use, ride hard on your suppliers, ensure quality assembly, test many vehicles, listen to complaints, DON’T EVER TAKE A CHANCE IN CHEAPENING THINGS THROUGH BAD DESIGN, such as the infamous GM intake manifold gaskets.

When you think about it, it’s all rather simple.

Testing is AFTER the fact. To make a reliable vehicle…you have to make design choices BEFORE the car is built. Obviously even if you do that…problems may crop up. You have to be able to make changes quickly.

Many years ago I read an article in WSJ. It was an article about Ford and Toyota. There was a bearing plant went on strike and Ford decided to continue building vehicles with bearings from another plant despite the fact that this plan had major quality control problems. Toyota decided to wait and buy a limited number from another plant that had higher quality. While Ford had higher sales numbers that year…5 years down the road they were having higher then normal transmission failures (the main place the bearing were used).

The biggest problem that GM/Ford and Chryco had over the years…were with ridiculous executive bonuses that forced the executives to make decisions that were in the best interest of their pockets, but NOT in the best interest of the company. Chryco has changed that model. Not sure about Ford. GM was forced to change with the government bailout. We’ll see what the future holds.

Good comments @db4690. Speaking of thermostats, that’s a good example. The thermostat on my 20 year old Corolla is original to the car. Never had a single problem with it. Am I just lucky? Or is it because the OEM thermostat that came with the car has a better design than other cars, or used better materials? Or it is the type of thermostat (the Corolla uses a “bypass thermostat”), or is it where in the cooling system it is placed?

Mechanics who work on cars day in and day out often have a different perspective than those who do not.

George, you want to see perspective in action? Try to rent a trailer from U-Haul to pull behind a Ford Explorer and you will be told no way. Do the same for a Mercury Mountaineer and there won’t be a problem even though these are identical vehicles other than badges and trim.
The rollover perspective is the difference.

One design, say for a thermostat, will fail at widely different times based on random factors, difference in use, and the normal statistical variation for seemingly identical item produced on the same line, the same day.

It’s The Owner. A Responsible Owner Makes The Most Reliable Car.

There’s Not A Hill Of Beans Worth Of Difference In Reliability Between Any Of The Best Selling Makes And Models When They Leave The Manufacturer As New. However, There’s A World Of Difference Between Owners. We Stand Witness To That Here Every Day.

The Owner’s Attention To Maintenance/Repairs And Taking The Time To Learn Car Basics (And Reading And Comprehending The Owner’s Manual), And Selecting Repair Shops With Competent Technicians Makes Or Breaks Reliability.

CSA

True, CSA - the biggest difference is the owner. I mentioned a while ago that a motorcycle mechanic noted that the bikes maintained obsessively by concientious owners seemed to last a LONG time, while the motorcycles owned by the ‘fix it when it breaks’ type owners often met an early demise.

It’s not the owner. It’s the vehicle when it comes off the assembly line.

All vehicle manufacterer’s have vendors that supply parts. This can range from gaskets, suspension, steering, brakes, cooling, HVAC, etc… It’s when the manufacturer demands from the vendor it’s only willing to pay so much for each component piece is where the vendor has to cut costs in order make a profit. So you end up with an inferior component in the vehicle off the assembly line.

Tester

However, There's A World Of Difference Between Owners.

I can show you COUNTLESS number of people who were staunch GM/Ford or Chryco owners…who are now buying Toyota/Honda/Nissan and have far better reliability results with these vehicles…I know I’m one of them…The OWNER didn’t change…but the vehicles did.

I use to feel the same way some 30 years ago. The first person who I finally listened to that a Nissan was far more reliable then my GM vehicles was a neighbor of my sister who’s a retired Master Mechanic for Nissan. Worked for years at GM dealerships…And even worked as a NASCAR mechanic. By far the most knowledgeable mechanic I ever new. At 70 he’s still working on cars and LOVES it.

While I agree 100% that the owner who maintains their vehicle better…the vehicles will be a lot more reliable. But that is just plain stupid to think that only Honda/Toyota and Nissan owners are better at maintenance.

True - if we assume equal maintenance, there are real differences that relate to everything Docnick mentioned. Part specifications, basic design, and assembly all play into it.

Because there are thermostats and there are thermostats. There are bearings and there are bearings. There are lighting control modules and there are lighting control modules.

Back in 2006 Toyota sold almost twice as many vehicles worldwide Chrysler. Also in 2006 Chrysler spent almost twice as much fixing their own cars under warranty as Toyota. I don’t mean this to say I’m a Toyota fan, just that it appears during that time period Toyota built better cars using better parts than Chrysler. I think that level of repairs while still under basic factory warranty speaks to build quality and parts rather than poor maintenance.

I seem to regularly run into Dodge pickups and SUVs that have strange lighting, door lock, and window problems, caused by a faulty central timer module. It’s a $350 part. I don’t think I’ve run into similar failures on Toyota vehicles. Perhaps if Chrysler had paid $500 for the part instead of $300 it wouldn’t fail as often.

As for the maintenance side of it, I think people who shell out $$ for a new top-end Acura, Lexus, BMW, etc are often educated people who understand cost of ownership and want to protect their auto by doing any and all recommended maintenance. People who get lured into a new car by a dealership offering a new car for $199/month can often barely afford payment and insurance and could give a darn about that scheduled maintenance booklet. As a result, they often end up owing money on pile of junk.

A lot of excellent comments here. One more that has not been mentioned. Cars that make only incremental changes year to year tend to benefit from what was learned in earlier years. American cars of the 40s-60s were quite reliable for their time, when bearings and manufacturing technology were not what they are today, but in those days, there was very little difference between two model years other than the size of the fins on the fenders and the shape of the tail lights. My dad’s '64 Chevy was basically the same car as his '54 Chevy once you got beneath the sheet metal.

Then US auto makers started trying to design cars starting with a blank sheet of paper and still get them to production within 18 months of conception. They would put young, green, engineers in charge of whole subassemblies because the managers thought they wanted “fresh new ideas”. That kind of design approach gets you a Chevy Vega or an American Motors Gremlin.

When today’s manufacturers say that the new model is “completely redesigned”, it is not true. And if it is true, you don’t want a car from the first couple of production years for that model.

Some parts just aren’t made to work right while other ones are as good as they get. If you look at some engine blocks, you can see major differences. I don’t like to see both sides of a cylinder wall. I want to know that the top of the cylinder wall has lots of support from a healthy looking deck. I would hate to make head gaskets that try to seal a cylinder wall that has a quarter inch of metal as the only material to cling to. It just doesn’t inspire much confidence.

I like mechanical controls for heater ducts. In the summer, the AC is either too hot or too cold. It isn’t much of a difference but I notice it. I never had that problem with mechanical controls. My 72 Caddy had a temperature wheel that wasn’t mechanical but it worked better that what I think we have today. Nero could fiddle all day with the controls on a 2013 Impala.

I believe Honda makes very reliable, and long lasting vehicles. They use higher quality parts overall, which fail less and last longer. Honda designers and engineers seem to know more about motor design and get more power from less displacement and incorporate high technology without hurting longevity and reliability, V-tec variable valve systems for example.

Failures of motorcycle parts can be literally “killers” for the rider. Perhaps Honda’s mentality in making motorcycles carried over into the making of Honda cars and other products. I owned a bunch of Honda motorcycles over the years including some 20+ year old classics. They all ran great, never leaked any fluids, and needed few repairs.

My experience with Honda cars has be the same as the motorcycles. About the only bad Honda parts are the auto transmissions in the Odyssey vans, which seem to fail at a higher rate than expected. This is likely to a component under designed for the loads put on it. No vehicle, and no manufacturer is perfect (which keeps mechanics in demand) but Honda ranks up there as one of the best IMO. If you want the secret(s) behind more reliable cars study Honda for some answers.

@MikeInNH Agree. First of all, testing is done at all stages of car production; the supplier and manufacturer relentlessly test compnents to make sure they last the intended life with a Six Sigma reliability. The assembled vehicles are then tested to death to make sure they whole assembly works.

In the sixties and seventies I worked for a company that had only Big Three cars as company vehicles. One of our managers spent some time in California and observed owners of Japanse cars piling on a lot of miles commuting with these tiny cars. So he bought his wife, who loved small cars, a Nissan. To both of their surprises, the little Nissan was not only light years better than the small cars (Big Three and European) she used to drive, but it was far better than his pampered Olds 88. From then on he bought nothing but Japanese cars.

A colleague of mine once talked to a couple of NipponDenso alternator designers. He said it was mind boggling what this company did to ensure their alternators were reliable and long lasting (two different things!), compared to US manufacturers of the same products.

My wife’s Nissan had the original starter fail after 16 years of use. The replacement was a rebuilt unit (not by Nissan) and lasted 1 year, to be replaced by the shop for labor cost only. At the time I felt the car was too old to justify a NIssan OEM replacement.

Like you, I categorically reject the UNSUBSTANTIATED claim that CSA makes that there in little or no difference in parts quality and that it’s all the drivers doing. I agree that a bad driver can speed up a car’s demise and reduce its day to day reliability. I achieved very reliable performance from my 1984 Impala, but I had to PRO-ACTIVELY replace a number of parts I knew were going to fail shortly, at a much shorter interval than those in a Nissan or Toyota.

Today that difference is less, but comparing a Ford Focus with a Mazda 3 for long term reliablity still shows a vast difference.

@tester Japanese car companies have a different approach to getting the parts costs down. They work with the supplier to manufacture it in the most efficeint way, and help with testing. As the suplier learns and reduces costs, the car maker wants a share of that cost reduction. It’s a cooperative effort, instead of playing one supplier off against the other. It is a win-win situation.

This process, until recently, was completely unknown to US manufacturers’ purchasing departments.

CSA- What maintenenance procedures do Subaru owners omit that cause all their head gasket failures?
A number of years ago my son owned a new Geo Prisim, a car with a mechanicly identical design to the Toyota Corolla. The only parts on that car that failed early were parts that GM put on it. In less than a year the Geo emblems fell off and the Geo floor mats wore through. At 7 years the radiator failed. I went to buy a new radiator and the auto parts store offered me two choices, a $109 one, or a $325 one. I asked why the difference and was told, well, they will both fit, but the cheap one meets GM specs and the other one meets Toyotas.

When the Japanese cars were taking over the California market the Yen/$ rate was Y360/$1 and the cars in Japan were usually scrapped by the time they had 100,000 miles on them. In 1970 the Japanese were driving automobiles with 350cc 2 stroke engines and 3 wheel diesel pickups that were hand cranked and required burning oily rags to heat the glow plugs. The automobiles they sold in the U.S. were their top of the line full sized models with over sized engines. Detroit was caught with their pants down when the oil crisis hit and the Japanese government supported the push to sell automobiles to the US while they continued to severely restrict American products from the Japanese markets. The situation regarding Japanese cars in the US is quite complex and just now we are benefiting from the Y90/$1 exchange rate that has Toyota and Nissan factories operating in the US. How reliable are the automobiles from these factories?