Originally Posted by 2014a6tdi

Now, I'm in Coastal California so perhaps take what I say with a grain of salt, but, with my old gas car I got my best mileage during the winter and there was a 5-10% drop off in the summer. I'd guess it due to ethanol or something added to summer blend.

With my tdi diesel I'm seeing the exact opposite where during the winter I'm getting 5-10% worse mileage than I did during the summer and here in CA we don't have winter/summer diesel blends because it just doesn't get that cold.

I realize there are heaters for the adblue, the diesel lines, the aux heater for cabin heat, etc. Perhaps that's what is holding the stats down in winter.

Even so, I've never seen the computer on a trip say more than 43 mpg which is absolutely murdering the EPA estimates for this car, so I'm quite happy. My combined is 37 mpg over the "long term" which is the EPA highway estimate.

This car replaced a Lexus GS 460 (premium gas only). Just did my taxes and can absolutely say with this car my fuel bill is basically 50% less and I really don't see a massive step down in performance.

Originally Posted by gk1

Yep in lovely NJ we are E10 year round and get hit with winter blend gasoline which doesn't help mileage...I'm not sure why yours was better in winter I don't know how they do things out in Cali and if there even is winter/summer blend for diesel either.
Also are you only using the trip computer because that tends to read about 5- 10% high...either way those diesels definitely get some damn good mileage, now they just need to bring over the bi-turbo diesels and things will get really interesting...

Originally Posted by 2014a6tdi

Perhaps its just the air conditioner then that knocked the economy down in the summer. But, you're right, we out in California do beat to different drum. In most parts of california, there is no winter blend diesel, its #2 year round because we don't really have the cold to bother with.

I'll run the numbers by hand in the future to see how far off the trip computer really is. I'm surprised to hear that its off by that much because the computer certainly knows the fuel flow and the mileage travelled, but, I'll test your theory. As far as $$$ are concerned though, for the same mileage I'm about 50% less in fuel costs. That's quite clear.

I'm very satisfied with the 3.0 as-is, I could care less about the bi-turbo especially in a very heavy A6. Speed limit is still 65, wink wink. Really I'm not a fan of forced induction in general, but, the world is going that way no matter how I feel about it.

Originally Posted by NoahWeb

"a very heavy A6" ???

The C7 is a great deal lighter than the C6 version. Weighed my TDI, full fluids, at 4,300 pounds. For a 5-star safety rated vehicle that returns an at pump average of 39+ MPG with quattro...I think we are sitting in tall cotton!

My calculation of 39.89 MPG was, again, the at-pump average. The DIS was 41.9...and error of ~1%