My car runs perfectly fine but I’m getting 22mpg 70% highway 30% city. Awful. 215k, I have original injectors. Probably time to send them to greazzer when I get a chance, but can’t imagine worn nozzles would cause such terrible mpg. My compression is great, I tested it before when I did glow plugs out of curiosity. Doubt timing chain stretch is a thing since it’s had Mobil 1 synthetic oil changes since new (family owned since day 1 and maintained) at 5k intervals.

Any ideas? My tire pressure is set all even. It’s literally a waste of money in fuel. I don’t drive over 75 which is about 2700rpms.

I’m also calculating the fuel from about a little above half a tank to right before the reserve light comes on I fill it up to get back to where I was with $30. I calculate the miles travel by the gallons to refill to the previous spot my fuel gauge was at. Wonder if that skews my results by not adding a full tank?

Also I have minimal smoke if any. I’ve gotten as low as 18mpg doing the same traveling. It’s despicable.

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Only diesels in this driveway.
2005 E320 CDI 243k Black/Black
2008 Chevy 3500HD Duramax 340k
2004 Chevy 2500HD Duramax 220k