14.7 MPG Highway - 17.7 MPG City....How??

How many mornings have you woken up to frost on your windshield?

 

Haven't scraped yet and I leave at 7am.

 

You must live at the beach. Remember that snow storm in 09 or 10?

 

My truck is bone stock and I never get better than 19mpg per tank.

 

I live in Chesapeake and yes, I remember, we got a foot of snow and a week later it was gone for us.

Winter for us is late Jan and Feb, by March its rainy and high 40s low 50s. Mileage improves after April.

 

He has a front bumper, rear bumper sliders, different wheel and tires and leds.

More weight less auerodynamic. Not even sure why this is even a debate.....

 

Not a debate. My stop and go city driving fuel efficiency dropped maybe 1-2MPG after bolting on thousands of lbs of shit and bigger tires. My highway MPGs are down 6+. How does that make sense?

 

I meant debate of people talking about sciencee of temperature and gas etc etc.

Honestly I don’t know your area of driving. Is is flat roads or constant up and down hilly areas, incline more than decline roads, speed limit change, aggressive driver that passes people. So many factors it ain’t funny. You changed your truck from stock that’s the big difference.

Are you calculating gas or looking at your dash?

I said in the first page. Your going way to fast on this truck. Sweet spot for decent mpg is 55-60mph. The faster you go you don’t exactly get better mpg, plus that front bumper don’t help you at all.

 

My taco hates the highway, above 65 and I might as well put a straw in my tank and start sucking it out myself.

Backroads doing 50-55, and I see great mileage.

 

Drag is not affected by the mass inside the vehicle. If you look at the equation for high speed drag you'll see there no mass in the equation:




Rolling resistance increases with increasing load on the vehicle, but it's a pretty small change.

Note that the drag force is a function of the square of the velocity, the difference between 55 mph and 70 mph is yuge.

 

There's an efficiency curve. It drops more drastically on the fast side of the speed scale than it does on the slow side. Bolting on "thousands of lbs of shit and bigger tires" just exacerbates the issue.

 

So that 75K lb truck versus that Prius? Really?

 

Only science you need to know is modded truck = Iffy MPG

 

It is all about the velocity, the drag coefficient and the frontal area. Look at the equation, where do you see mass?

 

Drive slower and report back, 70-75 is your problem. It's a v6 in a heavy truck to begin with and you added much more weight and made it less aerodynamic. The lower your rpms the better...i'm not sure what the sweet spot is but usually once you hit 2k and go over it drops.

 

Yep. Lifting the truck effectively increases the frontal cross section. Also, the roof rack.

 

Rolling resistance increased by adding weight + different tires. It is important.
Yes aero is the biggie and that light bar and bumper is big there too.

OP, looking at your truck I definitely can see you taking a big hit o

I don't have to look at that equation... I have it burned into my brain lol.
What is missing is accelerating that mass up an incline. Say a 5% hill for several miles.
You are right partly but so are several others lol.
Bottom line, the truck is not broke. It is totally within normal limits given the mods.

 

Not important at all, actually. It is a tiny, tiny factor.

Yep. By orders of magnitude at 70 mph.

 

Let's use an example, a stock Prius and a Prius filled with 75K lb of lead.
On level ground at speed then yes, there is a difference but not much all else being equal. Accelerating, meaning dropping to 55 then up to 75, accelerating from stop, etc is a huge difference. Going up a hill is huge also.
Again, his truck is operating normally given the mods performed.

 

Yeah, but what size tires are on the Prius filled with lead?