Why can't semi trucks get better fuel economy class 8 highway tractortrailers?

Answer 1

with modern trucks , and newer technology, semis are getting better economy. take into account that semis idle when parked to run heat or a/c, and the fact that a loaded semi grosses 40 ton, then compare that with a pickup running round empty and weighing about 4 ton. i think 6 to 8 mpg for a semi is pretty damn good versus 16 mile per gallon in a pickup and that pickup milage starts at the lowly Ford f150 with a 4.6 engine which has about about 40 horsepower versus a semi with about 500 horsepower. add to that, the extra equipment sometimes run on a semi such as a power takeoff,to pump hydraulics,or a freezer van that needs fuel to run the freezer motor . now ask why pickups and cars get so small an economy There are several ways to get better economy, and truckers do them all the time. The first one is to put an Auxiliary Power Unit on the truck. This is a little diesel powered generator, and it keeps your truck comfortable when you're parked. (It also lets you run your microwave oven, crock pot, refrigerator, big screen television--yes, there are drivers with big screen TVs hanging on the back wall of their sleepers--and all the other comforts of home, but that's a discussion for another time.) There are also Intelligent Idle systems. My truck contains Cummins' ICON Idle system. It's like a thermostat on a furnace. There's a thermostat on the back wall of my sleeper. When the temperature gets too far outside the range the driver set, the engine starts and runs just long enough to get the cab comfy again. I don't mind getting a little warm in there, so I just don't idle the truck unless it's really necessary. Modern aero cabs also give you better fuel economy. Another advantage of aero cabs is the cabs are lighter, which translates into more payload. That truck can weigh 80,000 pounds. Every pound the cab weighs is a pound you can't use for freight...and last I checked, no one's paying me to haul cab weight around. The gearing is also critical. So is running cruise control. If you properly set up the truck and you drive it with fuel economy in mind, you can easily pull 8mpg average out of it.