How to drive the mighty 335d Super-diesel to excellent FE. [xfloat=left]http://www.cleanmpg.com/photos/data/501/Passenger_Side_Rear_in_the_rain.jpg[/xfloat]Wayne Gerdes - CleanMPG - April 20, 2009 2009 BMW 335d – 27 mpgUS combined and worth almost 50 with a little work from you. Techniques Explained Basic accelerations - With no one following, acceleration from 0 mph can be accomplished with a light touch of the throttle and use of the paddle shifters to up shift from gears 1 and 2 when 1,450 RPM is seen on the tachometer. From gears 3 and 4 up shift via the paddle shifters at just 1,400 RPM and a light touch will maintain above 30 mpg during the acceleration. Once in fifth, shift via the paddle shifters at 43 mph and the BMW will maintain sixth gear with the iFCD holding above 50 mpg. Gentle acceleration up into the 48 mph + range during slower speed city/suburban cruise maintains this level of FE, but be ready for NICE-Ons for any slow downs. Fuel cut should only be used if a stop is required of course, and the paddle shifters can be utilized during deceleration to stay above 1,000 RPM. At speed FASing in the 335d is not only unwise per the manual (which specifies no flat towing), but impossible due to a shut down lockout at any speed other than stopped via the Push Button. As diesels utilize extreme lean-burn A/F ratios at low loads, the best practice is to get the heavy 335d rolling and maintain momentum with strict attention paid to DWL. City [xfloat=left]http://www.cleanmpg.com/photos/data/523/37_9_mpg_at_20_4_mph_-_NY_City_Rush_Hour_Commute_SMALL.jpg[/xfloat]NY City during Rush Hour FE test results - 37.9 mpgUS at 20.4 mph over 23 miles. A light touch of the throttle on any acceleration while using the paddle shifters as described above and moving to NICE-On’s for any slow down is optimal for this vehicle. If a lengthy stop is anticipated, go ahead and FAS at the light but remember that diesels burn only about a quarter the amount used by SI-ICE (gasoline engine) vehicles at idle. Additionally, it takes quite a bit of cranking power to turn the 335d’s 16.5:1 compression ratio over. Because of these factors, shutdown should only be utilized for stops longer than 20 seconds. Since you cannot FAS the 335d at anything other than a full stop, this technique was used only 3 times during the hour and 16-minute nightmare commute. There is a Neutral lockout below 3 mph until stopped so if you find yourself in this situation, open up an even larger than normal inner city buffer, accelerate to 3 + mph and than NICE-On Glide back down to 0 mph to remove the big 6-speed AT and related power losses from its TC when dealing with stop and go traffic. And it is imperative that your mindset sticks to 3-Lights out anticipatory focus. You simply have to catch more green lights in the inner city or your segment is going to be wiped out. 2009 BMW 335d - NY City during Rush Hour FE Testing ----Leaving a 7-mile FE test loop deep into NY City’s inner sanctum.-------NY City’s I-495 during the city’s afternoon Rush Hour stop and crawl. Both part of the 23-mile inner City/Interstate rush hour FE testing. Highway [xfloat=left]http://www.cleanmpg.com/photos/data/523/53_4_mpg_at_64_8_mph_SMALL.jpg[/xfloat]All highway drive on the way back from NY City. 53.4 mpg at 64.8 mph over 120 miles. Unfortunately this included a strong tailwind aid While on the way back from NY, we were experiencing strong tailwinds allowing far above normal FE results for the speeds we were traveling so I did not report the results of the entire drive back given they were very unrepresentative. We were traveling with average speeds between 65 and 70 mph including the stops to swap on both ends and still achieving FE results between 48.0 and 54.7 mpg! While on the highway in a climb, DWL to a comfortable minimum speed and hold. Once the crest is reached, a NICE-On can be used if there is a long and relatively steep descent on the backside little or no acceleration to reach an acceptable top speed for the rest of the hill or mountain. For steady state cruise, choose your desired FE per the analog iFCD and drive. Unfortunately, the steady state while DWL FE testing results occurred in 38 to 39 degree F temperatures with a 15 + mph strong side wind so the results shown will not be representative of actual unfortunately Reasonably steady state FE capability Column1Column2Column3mphmpgUSNotes 40465th Gear and ~ 1,250 RPM 54506th Gear and ~ 1,250 RPM 60416th Gear and ~ 1,500 RPM 70386th Gear and ~ 1,775 RPM There is a warm-up hit but it is not nearly as intrusive as that of a Hybrid or most conventionally powered automobiles. Just work though it and move on gently. A DPF regeneration event is much more damaging to FE. While on the way home after an overnight rest stop, only 30 to 35 mpgUS on the iFCD was achievable for close to 20 miles. The DPF regeneration event is based on DP across the filter and if it happens at lightly loaded highway cruise, it can last for upwards of 20 miles. That 100 mile segment ended up at just 43 mpgUS because of this behavior. We were fortunate not to have encountered one of these events on the drive up to NY as it likely would have prevented completion of the trip on a single tank. Max fuel tank capacity and fuel starve The BMW 335d is equipped with a 16.1 gallon tank and holds at least 16.485 gallons to near fuel starve as we discovered. With the manual stating a 2.1 gallon reserve and seeing the Low fuel light at exactly 100 miles DTE while still holding 49.0 mpgUS from the FCD, it is wise to heed the warnings. When near 0 DTE, you will see positive numbers and – (less than 0 miles DTE) depending on terrain. In either case, fill up before you get to that point!