[doc5339]

I just averaged 40.5 mpg indicated for 60+ miles doing between 50 and 60 MPH on a state road at approx. 60 degrees F.

[335dFan]

I haven't actually done this yet but have plans to do so this August, whereby I drive across country on Interstates with little to no stop and go except for refueling and bio breaks. I believe that I can achieve near 40 mpg without particular attention to maintaining a certain speed, whether it be 55 or 65 or 75, but keeping with the reasonable flow of traffic. I'm sure one could achieve even a bit better by sticking absolutely to 55, but I would fall asleep at the switch. I say this with a fair amount of confidence because my two best tanks to date (37.1 and 34.9) have been mixtures of city, suburb, and highway, and I definitely was not going easy on the go pedal, having recently installed the JBD, for the 34.9 one. Consistency and maintaining the flow seems to be the key to getting over 600 miles on a tank. I calculate my MPG the old fashioned way, by hand. Miles driven since last fill / gallons to refill.

[Persian Whisperjet]

Driving from D.C. to Memphis last month I got 37.5 mpg, then 41.7 on the way back via St Louis. I put some air in the tires in St Louis so that may have affected the results, and I always add a dash of XPD at fuel-ups.

[335dM]

Originally Posted by maswastage

In my experience, driving 75 mph even in below freezing temperatures still nets 42+ mpg. Oddly enough, driving 65mph didn't seem to improve it by too much, maybe up to 44 or 45.

How can you achieve 42+ mpg at 75mph?????

[Puerto Rican 335d]

Get a bigger intercooler amigo 335dM. and you will see better mileage results, as I sated on a blog my car clocked 46 mpg at 70-75 mph but remember I dont have the roads you guys have but indeed I have better mileage since Ive intsalled the IC

[Jhayd11]

Don't forget to check tires and tire pressure. Run Flats, bad tires, or under inflated tires will prevent you from really getting up there.

I have Run Flats because there are no pull off area's around most of DC and a lot of pot holes. Best I get is 36 mpg average.

some other things people forget.

empty your trunk, go easy on the AC (shut off the back seats)

draft.

Find your car's sweet spot. Different tires, weight, suspension will change the top speed at lowest RPMs. Find where it is doing best, switch to manual mode to lock it in 6th (no auto down shifting for soft hills) and cruise.

[Thud]

I think that you'd get the best mileage if your engine is right at its torque peak in 6th gear. But I could be wrong.

[maswastage]

Originally Posted by 335dM

How can you achieve 42+ mpg at 75mph?????

I don't know. I didn't really do anything special. This was from a road trip back in November; DC to Knoxville, driving over the mountains, with 2 of us and luggage in the car, cruising between 65 and 80. The trip back was the most accurate mpg-wise because I filled up right outside of Knoxville and then again the next morning after arriving in DC (so it was as close to pure highway as I've ever had for a full tank) and the pump-calculation was 40.9 mpg. Trip computer showed 39.1 i believe. On the way to Knoxville, for the first 75 miles coming out of DC, going uphill into the mountains, the trip computer showed 42 mpg at 69 mph.

Strangely enough, the next time we made the trip in March we got only around 37-38 mpg. Of course, the day after we got back I found out one of my tires was very under inflated, so there you go.

[totitan]

The surprising thing to me is that my 12 VW JSW tdi barely gets better than my 335d. At a steady 75 on cruise the VW gets 42-44 and the d is high 30's. Not bad for twice the power in a heavier car.

[chau]

I'm getting 29-30mpg average with 5 days of heavy Philadelphia traffic. Guess it's not bad.

[AzureHaze]

Averaging 27-30mpg for me in fantastic SoCal traffic.

[trsaz23]

34.5 mpg @ 74.5 mph (average) with cruise all highway up the mountain to Park City and back down ..... not as good as my Jetta but still for only 18k miles on the car, not too bad.........LOVE MY 'D'

[335dFan]

On my first lengthy road trip yesterday from Annapolis, MD to Asheville, NC (545 miles with a couple of short off-interstate forays), I got 39.72 mpg hand-calculated. JBD set at about 60%. Previous fillup before starting was 32.5.

[maswastage]

Originally Posted by 335dFan

On my first lengthy road trip yesterday from Annapolis, MD to Asheville, NC (545 miles with a couple of short off-interstate forays), I got 39.72 mpg hand-calculated. JBD set at about 60%. Previous fillup before starting was 32.5.

Very nice! Good to see my ~40 mpg road trips aren't a fluke.

I made the DC - Knoxville trip again a week ago, with tires properly inflated this time, and once again saw roughly 40 mpg, through mountains, with speeds averaging 75. I didn't get a good all-highway fill up this time so I'm basing this on the trip computer, which showed 39.1 to 40.5 for about the 450 mile stretch on the highway (and knowing that my computer consistently reads .5 to 1.5 mpg below actual). On the way back, even with about 2 days of 75% city driving thrown into the mix after arrival in DC, my next fill up still manually calculated at 38.8 mpg.

[335dFan]

Ok. Last post on this subject. Unless it gets better. Got 40.0 mpg even on a 490 mile trip today from SC to MD. There was some stop and go on 301 in Waldorf toward the end or it would have been a tad better. Went generally about 2-3 mph over the limit most of the time without cruise control, but I did not baby it. So that was either indicated 60 mph, 65 mph, 70 mph, or 75-80 mph depending on the prevailing speed limit on the interstate. Included at least one rather brisk start at one intersection on 301. These cars are really amazing. I even got 36.4 on a tank that included driving from Asheville to the Tail of the Dragon and back. Some spirited mountain driving. The worst I have ever got is 26 point something that included a day at HPDE last September.

[Puerto Rican 335d]

I hate you guys I cant get those numbers since my island is 100x35 oh well but I got beautiful beaches and women!!! LOL

[Mark M]

Commented in another thread, my father brought my car from Charlotte NC to Lancaster PA and averaged 40.5 mpg running Shell Diesel fuel.

[Puerto Rican 335d]

Mark did you get your car finally?

[Mark M]

Not yet. Anticipation is killing me.

My father took it straight from Charlotte NC to our local PA dealer (empty def tank, thanks previous dealer)

My local dealer is going over it now, making sure campaigns are up to date, flushing urea, and some other little things, said it needs NOx sensors too.

Fingers crossed that I'll have it by the weekend.

[Puerto Rican 335d]

be ready to stand by, those NOX sensors are NOT available as we wish but can be flown overnite , Yes BMW does that cause it has happened to me here in Puerto Rico, cant wait till warranty expires to explore the DPF removal etc etc!!