Aerodynamics vs. Appearance

The problem is the type of miles you're running. If you're getting 5.1 with a Cascadia, aerodynamics isn't going to help you! Other posters have pointed out that old trucks would be getting 7 pulling a connie. You're probably doing a lot of city miles and stop and go. The fuel mileage just isn't there.

 

Good luck, I think you're dreaming on the MPG's....consider 6 more likely...(I run containers 300 miles around Chicago...that's the fleet average for the company I'm leased on to, all 2000+ model year tractors....the DPF and DEF trucks are in the shop...A LOT).....MAKE SURE THEY HIGH IDLE WHEN STOPPED ...cant be stressed enough....

I used to run flatbed OTR for Maverick (brand new Cascadias all new fleet) OTR, we were averaging in the high 7's as a fleet (2,000 trucks, all automatics, 64 mph 1500rpm limit, mix of DD13 and DD15) but that was OTR, the dedicated accounts (300 miles or less) usually had much lower fleet average....

All the fairings are useless for short haul...

 

Why is your mileage so terrible currently? You're at least 1.5mpg short of what you should be with good driving and low idle time.

I'd get a nose cone and look at addressing your terrible mileage reasons as it is.
A battery powered cab AC system and a Webasto parking heater would be wise investments to save you big fuel money long term....in addition to saving on emissions system problems.
You DON'T want to be idling a DPF or DPF/SCR truck!!

 

Running the miles the OP stated, (300 a day), will not give good fuel mileage. Just won't happen. Too much stop and go, and depending on where he's located, he may be in hills all the time.

I do local work. Run around 350-450 miles a night total. Most of my trips are less than 100 miles loaded at 80k, with a 50-75 mile bounce in between loads. Running the speed limit, I'm only doing 5 to 5.5 mpg on a good day.

On the rare occasions that I run a longer trip, say 600 miles in a day, being loaded @80k for 400 miles, my mileage goes into the 6 to 6.25 mpg range.

So one should not assume there's automatically something wrong with a truck when they're told fuel mileage numbers that would be considered poor.

And all the aerodynamic crap out there may help, but only a little bit. Performance mods will get a better return on investment, but if the truck is new, that's a no-go.

 

Probably worth looking at tires, however. Rolling resistance makes a bigger difference on local runs.

 

Let's face it though, ALL efficiency improvements are worth it on the bottom line with fuel consumption....

 

Absolutely not! If you spend $6,000 on tires to get a lower rolling resistence, but the tires don't last as long as a $3,000 set, and you save .1 mpg, driving the miles this op does, it will have cost $3,000 to save $451 in fuel. That's not worth it!

 

You aren't very familiar with mathematics I take it? Bean Jr. already gave an example but this needs to be emphasized, especially for all those bean counters pushing these new regulations on the industry and the companies bending over backwards to accommodate them.

There are people who drive long hood Peterbilts and Kenworths with old CAT's and Detroit's that get just as good fuel economy as those with super singles, running a Paccar or MAXXFORCE or whatever else they make as an excuse for a motor these days.

It mostly comes down to driver skill.

 

Bottom line, running local (300 miles around a large urban center), stop and go traffic will NOT allow the same fuel economy as OTR, and aerodynamics will NOT play a part in your fuel consumption. If you want to throw good money out the window, it's up to you. But the numbers simply don't add up.

If you were hitting the slab, 500+ miles a day in open road, then yeah, I'd be right there with you on this...