Guess what the "Least Efficient Truck" is...

[Droid]

I bought mine for fuel economy. And now I'm PISSED.

 

[whtrapta]

I still am determined my truck lies to me and I'm really getting 20 mpg all the time. 100mph, 20mpg.

 

[BIRDMAN]

4.10 gears don't help over 55

 

[pirate air]

Resistance caused by air drag is definitely the number one thing that kills the Raptor's (or any vehicles) mpg the faster you go. NV Guy sounds right that velocity is ^2 for figuring air drag resistance. You go two times faster, its four times the air drag. Once a stream line goes turbulent, getting anything laminar again (in the Raptors case) is impossible unless you slow down. So I guess in other words, I doubt y speed that is faster, will create less resistance then x speed that is slower.

 

[BMart]

Wht, you can double check it with good old lame ass math. Next time you fill up, put the nozzle back when it stops itself and then reset one of the odos and your MPG computer before driving off. At your next fill-up (preferably at the same pump), when the nozzle stops itself, check the gallons you just put in. Divide the miles on the odo by the gallons put into the truck. Then cross reference that number with what's on your computer. If it's different, then she's a lying *****.

 

[Droid]

Dynamic pressure = 1/2 ρ v^2

ρ = air density
v = velocity

Total drag = Cd * SA * 1/2 * ρ * v^2

Cd = coefficient of drag
SA = reference surface area

Raptor has a whole bunch of Cd and a whole bunch of SA which adds up to not much MPG.

There's no point in paying attention to anything other than v^2 though, for example:

at 60mph through still air v^2 = 3600
at 70mph through still air, v^2 = 4900
at 80mph through still air, v^2 = 6400

(Normally you don't use mph in dynamic pressure calculations, but it makes no difference for comparing two values.)

The big kicker on this in my opinion is let's say you take a roundtrip against and then with a 10mph wind with a ground speed of 60mph...

Into the headwind = airspeed is 70mph, so v^2 = 4900
With a tailwind = airspeed is 50mph, so v^2 = 2500

Aerodynamic drag is the lion's share of retarding forces at highway speed....something like 60-70% at 60mph iirc.

So the drag force is doubled with only a 10mph wind. Hence why you should never make claims of "I get XXmpg going XXmph" unless you drove one section of road several times back and forth.

 

[Hockster]

Good thing GM quit making the Hummer or it would still be at the bottom... lol

 

[SERG09]

This 6.2 does better than my old H2 in terms of gas mileage. Kinda twisted but I wear this "least efficient" as a badge of honor. Be a shame to let perfectly good, expired dinosaurs, go to waste

 

[SilverBolt]

Dynamic pressure = 1/2 ρ v^2

ρ = air density
v = velocity

Total drag = Cd * SA * 1/2 * ρ * v^2

Cd = coefficient of drag
SA = reference surface area

Raptor has a whole bunch of Cd and a whole bunch of SA which adds up to not much MPG.

There's no point in paying attention to anything other than v^2 though, for example:

at 60mph through still air v^2 = 3600
at 70mph through still air, v^2 = 4900
at 80mph through still air, v^2 = 6400

(Normally you don't use mph in dynamic pressure calculations, but it makes no difference for comparing two values.)

The big kicker on this in my opinion is let's say you take a roundtrip against and then with a 10mph wind with a ground speed of 60mph...

Into the headwind = airspeed is 70mph, so v^2 = 4900
With a tailwind = airspeed is 50mph, so v^2 = 2500

Aerodynamic drag is the lion's share of retarding forces at highway speed....something like 60-70% at 60mph iirc.

So the drag force is doubled with only a 10mph wind. Hence why you should never make claims of "I get XXmpg going XXmph" unless you drove one section of road several times back and forth.

Droid,
It's Friday morning and you made my brain hurt. lol

 

[JP7]

Dynamic pressure = 1/2 ρ v^2

ρ = air density
v = velocity

Total drag = Cd * SA * 1/2 * ρ * v^2

Cd = coefficient of drag
SA = reference surface area

Raptor has a whole bunch of Cd and a whole bunch of SA which adds up to not much MPG.

There's no point in paying attention to anything other than v^2 though, for example:

at 60mph through still air v^2 = 3600
at 70mph through still air, v^2 = 4900
at 80mph through still air, v^2 = 6400

(Normally you don't use mph in dynamic pressure calculations, but it makes no difference for comparing two values.)

The big kicker on this in my opinion is let's say you take a roundtrip against and then with a 10mph wind with a ground speed of 60mph...

Into the headwind = airspeed is 70mph, so v^2 = 4900
With a tailwind = airspeed is 50mph, so v^2 = 2500

Aerodynamic drag is the lion's share of retarding forces at highway speed....something like 60-70% at 60mph iirc.

So the drag force is doubled with only a 10mph wind. Hence why you should never make claims of "I get XXmpg going XXmph" unless you drove one section of road several times back and forth.

I agree with (Einstein). My mileage answer remains the same when questioned:
I've got her down to about $20/hour.