Where 7 mpg is Good
I saw on an older topic where someone mentioned they wished their was a real truck driver on site for feedback. It got me to thinking you might be interested in my "Work Drive".
Im a contractor with a large transportation company who runs the same terminal to terminal run every night. I thought you might be interested. Vehicle - 2006 Freightliner Columbia with Double 28' Pups. Weight - 20x typical car (53,000-80,000 lb) Rolling Resistance - 22x typical auto (22 tires with 4x the rolling resistance each) Air Drag - 12x typical auto (115 sq ft x 0.68 cd estimate) Powertrain - 470/515 bhp - 1650 torque (Increased output in cruise) 14.0L S60 Detroit with 13-Spd Double OD Trans (0.73 Top Gear). Drive Tires - Michelin XDA3 275/80R24.5 (493 rpm) Engine Rpm - 1403 rpm @ 65 mph (Factory Spec with brand new tires) Run - 202 mi x 2 over mixed roads with a maximum of 4 hours run time for each leg. Primarily rural non-limited access 4 lanes with a 65 mph limit. Driving Technique - Get it over the top at minimum rpm in top gear and give minimum throttle (Sometimes none) to reach 61 mph by next flat. I use moderate throttle in lower gears leaving redlights in deference to the drivetrain (20,000 lb of torque is hard on ujoints). 1400-1600 rpm shifts in lower gears. 1300-1500 shifts in uppers (I can split these gears). Note: In a 13 speed you have - A low you only use in extreme situations, You normally use 1-4 and then change ranges and go through 5-8 (Which are the same locations 1-4). You farther have a seperate OD on the back of the trans that only works in the "upper" gears which allows you to "split" the upper gears. Cruise Speed - 1350 rpm (61 mph with current tire wear) where legal. Average Speed - 58 mph Note: The truck averages the best at 61 mph due to forced downshifts on hills at lower speeds. Mpg - Average 7.2 mpg (6.8-7.3) Mpg Various Cruise Speeds - 1200 rpm (54 mph) - 7.5 mpg 1250 rpm (56 mph) - 7.8 mpg 1300 rpm (59 mph) - 8.0 mpg 1350 rpm (61 mph) - 7.8 mpg 1400 rpm (64 mph) - 7.5 mpg 1450 rpm (66 mph) - 7.2 mpg 1500 rpm (68 mph) - 6.9 mpg 1550 rpm (71 mph) - 6.5 mpg Note: this includes an average of 10 stops per trip (Stop Signs, Lights, Scales) and approximately 1 gal used at each end for assembly and disassembly of sets. |
Nice info.
Why do you peg the rolling resistance so high though? Large diameter high pressure tires with a hard compound should have less RR than a car tire. |
Yeah rolling resistance is kind of irrelevant anyways, the main point should be that per the weight, a semi truck is far more efficient than MOST cars and light trucks.
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nice info... if a truck company can crack 10mpg on those things, they will make a ton of money
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Somehow it's still more cost-effective by truck than by railway transportation!
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Great compilation of data! Thanks!
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Imagine the mileage you could get in a car if it was very aero and driven like the trucks, especially one with all of the high mileage tweaks used by truckers.
regards gary |
i'd say 7 is good. i drive a straight truck w/ a refer(cold) unit. our trucks get from ~4 to 6mpg depending on the route, but being local delivery, we have many more stops than you do. i've often wondered what we could achieve w/out the refer running.
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