Originally Posted by Cobb
Good points everyone. I too have wonder the same and mpg from a car. It seems for the most part with the advancements you can get a fuel efficient car pretty cheap that has good performance and does not require much maintenance.
The hybrid and diesel on that note looks less favorable to own. My family has had diesels and although they do not need spark plugs, they need glow plugs. Instead of a tune up they need the injector pump rebuilt. Less maintenance, but when it was needed it was more expensive.
The insight seems to be similar. It seems all of the Hondas are cursed as they use the same IMA system and on top of that the gen 2 requires the cvt to be serviced almost every oil change. Thats another 30-55 bucks on top of the oil change premium.
Cobb - the modern common-rail turbo diesel is a very long way away from old diesels of yesteryear. Not sure about injector pumps rebuilt, but the variability in trouble-free ownership is a lot wider than gasoline/ petrol motors.
From my own experience, I had virtually no issues in over 100K miles with the diesel Yaris (currently smashed up on my drive, awaiting an insurance payout after someone hit it while parked). It has needed glow plugs at 110K miles, and it likes new engine oil every 5K - and a fuel filter every 20K. The motor oil comes out completely black even after 500 miles, which is normal - but the motor is otherwise fine (though it belches out soot like crazy under load - also normal). Don't forget also that the glow plugs are for starting only, once the motor is running, they are off, and the motor burns diesel under heat and compression alone. Each glow plug is essentially a heating coil.
The fuel delivery is via a high pressure fuel pump to a series of piezo injectors - this is a very costly thing to repair if it fails, but the Toyota has been perfect.
The TDIs over the last 5-7 years have had DPFs (diesel particulate filters). These are where most of the reliability problems now lie. This is a regenerative filter that catches soot and unburned particulates at sub optimal combustion periods, and then burns them off at the right time. It has an injector in the DPF that squirts diesel in to the exhaust located filter, and it all gets burned off - normally as a big puff of soot on the highway at certain times. The smokey exhausts are now a thing of the past in cars fitted with a DPF
The problem comes when the thing gets clogged in short urban journeys, and doesnt have the opportunity to regenerate. When this happens, the diesel squirted in can make it's way to the engine oil, filling up the sump too much, which then leads to major problems.
These issues have been made worse by the proportion of biodiesel in the mix, to the point where they are probably no longer worth buying unless you do a lot of highway mileage.
They are also hugely dirtier than petrol engines.
So, in summary, petrol continues to be cleaner, simpler and cheaper to fix usually. Diesel is a fantastic fuel when executed well, used in the right conditions - though I believe diesel is rapidly coming to the end of it's run in the main, due to regulatory shift, and the inability of optimisation by manufacturers over time in the main.
The best TDIs were (in my opinion) made between about 2000 and 2007 before certain regulations and DPFs came in.
We know that TDIs were most widely promoted in the Euro area, and it is likely that over the next 10 years, the numbers on the roads will rapidly diminish; especially since this ridiculous VW fiasco, where clearly all the manufacturers are doing the same thing. VW were (and no favouratism at all here) instrumental in perfecting the turbo diesel, especially the 4 cylinder variant, which is the most common.
Diesels provide a very comfortable highway drive, revving low at speed, and having a large amount of torque for good acceleration at lower RPM without the need for changing gear. The standard sedan such a Passat, will cope very well with a 4 cylinder 2.0 TDI, less even these days, perhaps even 1.6.