I have a diesel I enjoy much. But, it is a Kobota M4030 5 cylinder farm tractor. Love it.
But, seriously, friends who had diesel Oldsmobile cars years ago had trouble with them and that turned me off. My family has diesel trucks, however. Ford F-250 Powerstroke and Dodge Cummins. Both have been extremely reliable. Many hundreds of thousands of miles with only routine maintenance.
Now that we have turbo diesel direct fuel injection cars like the VW TDI, I am gravitating back in that direction. I do have a gasoline turbo Mazda car that has direct injection, which is only one step away from being a diesel. it has been the most reliable car I've ever owned, despite that it is a performance car that I have "enhanced" in many ways to raise horsepower considerably.
A couple thoughts about the technology:
Direct fuel injection injects the fuel directly into the cylinder rather than through the intake manifold or throttle body. The fuel is under extremely high pressure - about 1,500 to 2,000 psi. This allows very precise metering and control of the fuel, very fine atomization of the mixture, precise changes in air to fuel ratio depending on operating conditions, allows variable valve timing to control all aspects of engine operation, and is what drastically increases both fuel mileage and power.
It is complex, however. Because there is no fuel ever going through the intake manifold or through the intake valves (only air), there is no cleaning of the passageways or the back side of the intake valves. They get gummed up over time. Fuel injector cleaners and additives in the fuel tank only clean the injectors. They do nothing otherwise I do nothing to touch this grime. It must be manually cleaned by removal of the intake manifold and using high pressure blasting techniques (usually ground walnut shells) or extremely strong solvents.
This is costly. For most people it has to be done by the dealer. I can do it myself. I can't speak to how frequently this type of cleaning is required in diesel engines. In my direct injection turbo car, it has to be done about every 45,000-60,000 miles.
The other thing is that diesel and gas direct injection engines tend to be turbocharged. That is a good thing and a bad thing. I love turbos. They can make a small displacement engine behave like a big V8 in power while still getting good fuel economy when cruising. Turbos spin at over 100,000 rpm and because of the high rpm tend to have a useful live of between 60,000 and 100,000 miles. To preserve their life it is very important to have regular oil and filter changes, more frequently than with non-turbo engines (every 3,750 miles in mine). It is best to run full 100% synthetic oils like Mobile 1 or Shell Rotella T-6. The temperature of the center shaft bearings in a turbocharger approaches 1500 degrees F. Ordinary dino based oils can break down under that heat. If that happens, the turbo can go out very quickly.
Is this technology worth a slightly more frequent oil change interval, a higher grade oil and a bit more maintenance? I say absolutely. My little Mazda 3 is making about 350 horsepower and still gets 28-29 mph on the highway. Even when I get aggressive with the "go" pedal, it still gets about 22 mph. It can go close to 160 mph and runs the quarter mile in 13.2 at 108. I now have had the car seven years and have 115K miles on it. Other than routine maintenance and recently finally getting the turbo rebuilt, it has been trouble free.
That level of performance may mean nothing if you are looking at a VW TDI, but what it means is that the technology is fully developed. The cars are very reliable, combine high mileage with good pickup, but are complex.
I could see a VW TDI in my future.
