
Originally Posted by
Outrider6
In my view, the current JSW's common rail diesel has yet to prove its durability. It has a fine heritage...previous VW diesels have been paragons of reliability. But those engines don't have the specific High Pressure Fuel Pump (HPFP) that current common rail TDI engines have.
HPFP changes are expensive for worn or failing units, but it's much worse if they do fail. Catastrophic HPFP failures have already occurred, requiring a replacement of the entire fuel system, which costs about $10K. Some of these failures are due to mis-fueling, but other failures seem to be unexplained. (Check the forums on other VW diesel sites for more info.)
The current TDI engine is more complex than the 2.5, since the 2.5 isn't using a turbo, nor an HPFP. The 2.5 does seem pretty reliable and has been around since about 2005, so there are high mileage examples floating around.
The fuel savings issue isn't as huge an advantage as you might think. Let's say a TDI gets 40 mpg and a 2.5 gasser gets 30 mpg. In 120,000 miles, the 2.5 burns 4,000 gal of fuel, but the TDI only burns 3000. That's 1000 gal in favor of the diesel, which is nice. But the actual fuel costs are different between the two and they do matter.
Use $4.00 per gal for regular unleaded and $4.25 for diesel. Fuel costs are $16,000 for the gas, 12,750 for diesel. It's $3250 cheaper for fuel, which is good, but... the TDI will cost more than a 2.5 will. If that acquisition cost is more than the fuel savings, where's the actual advantage? Though VW packaging complicates the comparison, you can buy a 2.5 for about $20K list, but the cheapest TDI is $25K. You're kidding yourself if you don't factor the diesel's higher acquisition cost (whatever it actually is) into the equation.
I really think that the maintenance will be the deciding factor in lifetime costs and that the TDI's complexity will erase the fuel savings due to maintenance needs. (Remember the diesel has an exhaust particulate filter that won't last forever.) The 2.5 is a simple, but modern, engine. It's powerful @ 170 Bhp. It does this with displacement, not with a high RPM blower sitting in a hot exhaust stream. A 2.5 can't blow a turbo it doesn't have.
Please don't take this as diesel bashing though. I own a TDI JSW. I simply bought it without the expectation that it would be radically cheaper to own than a gasser. I love the torque and I drive it like I stole it. (Not really, but I'm not hyper-mileing it either.)
You misread my text on using cars, but you still have the right answer...sorry my writing wasn't more clear.
"I'm also careful to use the gasser for short trips..." means that I drive a gasoline fueled car on any short trips.
"... and the TDI for anything over half an hour" is my way of differentiating short from long, and says that I'll take the TDI if I think I'll be running the car constantly for half an hour or more.
"Diesels work best if they warm up, something they probably won't do on very short trips" reinforces both points.
Hope the clarifications make sense...