Understanding vehicle efficiency, and its effect on payload

[Scott Brady]

I did a technical study on this topic just over a year ago, but thought some of you would enjoy the analysis.

Topic: Expedition Vehicle Fuel Consumption Rates and its impact on GVWR


Given all vehicles listed were completing a 1000 mile expedition fully self supported, in which all vehicles attained EPA city mileage. The 5gallon Jerry Can requirement is based upon all of the vehicles having the same sized gas tank as the Tacoma 6cyl Xtra Cab. The Tacoma 6cyl is the reference vehicle.


Reference:
Unleaded/Petrol Fuel: 6lbs per U.S. Gallon
Total Gallons Required= 1000 (miles traveled) / EPA (City) Mileage


Results:



Vehicle EPA (City) | Total Gallons | Fuel Mass | Mass Variance | 5gal Cans Req.
Tacoma 6cyl 17 | 59 Gal | 354 lbs. | Reference | reference
Suzuki Sidekick 22 | 45 Gal | 270 lbs. | -84 lbs | -3
Tacoma 4cyl 18 | 56 Gal | 336 lbs. | -18 lbs | -1
Tundra V8 15 | 67 Gal | 402 lbs. | 48 lbs | +2
Land Cruiser 13 | 77 Gal | 462 lbs. | 108 lbs | +4
Discovery II 13 | 77 Gal | 462 lbs. | 108 lbs | +4
Hummer H2 8.5 | 118 Gal | 706 lbs. | 352 lbs | +12


Payload Comparison (lbs.):

Vehicle | Payload | Fuel as a % of payload | Payload Remainder
Tacoma 6cyl | 1,585 | 22% | 1,231
Suzuki Sidekick | 898 | 30% | 628
Tacoma 4cyl | 1,630 | 21% | 1,294
Tundra V8 | 1,525 | 26% | 1,123
Land Cruiser | 1,470 | 31% | 1,008
Discovery II | 1,600 | 29% | 1,138
Hummer H2 | 2,200 | 32% | 1,494


General Conclusions:
- Available payload is a must greater factor than MPG in this study, unless fuel cost, or environmental impact is considered. For example, the H2 Hummer uses nearly 40% more fuel than any other vehicles in the study, but it also has the highest Payload Remainder.
- The vehicles at the two extremes (Hummer and Sidekick) both had fuel payloads over 30% of available payload capacity
- The Tacoma proved to be the most frugal selection, using much less fuel, while still having a high Payload Remainder.
- The Discover II also did well in the Payload Remainder, but suffers from poor economy based on the size of the vehicle.

[The BN Guy]

Are you using sticker mpg or estimated for modified vehicles? I think I'll try and put some numbers together for an Xterra, Pathfinder, and a Frontier to see how they rate.

[Scott Brady]

Are you using sticker mpg or estimated for modified vehicles? I think I'll try and put some numbers together for an Xterra, Pathfinder, and a Frontier to see how they rate.

Cool! I used MFG sticker MPG for city.

[flyingwil]

Scott, You seem to know a lot about this and great topic, BTW. My question is in reference to the payload. Are you finding variences in manufacturers in regards to wheather the max payload includes the fuel supply as to not included?

I just never thought to include the fuel quanity in my tank to figure out the max payload I could load. I am relating this to flying as well, but with flying it is much easier to determin the quantity of fuel you have on board. Also the manufactures have different weights for "wet" and "dry" configurations. So, with that said, I to am assuming that the payload doesn't include oil's as well. Am I correct?

I guess it is time to pull out the good old owners manual and find out for my self.

WIL

[pangaea]

Wil,

Payload is typically determined as GWV - Curb weight. Curb weight is determined as the weight of the vehicle in stock form with an average driver (175 lbs, IIRC) plus a full tank of gas.

[flyingwil]

Wil,

Payload is typically determined as GWV - Curb weight. Curb weight is determined as the weight of the vehicle in stock form with an average driver (175 lbs, IIRC) plus a full tank of gas.

BINGO! Exactly what I was looking for thanks!

[dieck]

I did a technical study on this topic just over a year ago, but thought some of you would enjoy the analysis.

Topic: Expedition Vehicle Fuel Consumption Rates and its impact on GVWR


Given all vehicles listed were completing a 1000 mile expedition fully self supported, in which all vehicles attained EPA city mileage. The 5gallon Jerry Can requirement is based upon all of the vehicles having the same sized gas tank as the Tacoma 6cyl Xtra Cab. The Tacoma 6cyl is the reference vehicle.


Reference:
Unleaded/Petrol Fuel: 6lbs per U.S. Gallon
Total Gallons Required= 1000 (miles traveled) / EPA (City) Mileage


Results:



Vehicle EPA (City) | Total Gallons | Fuel Mass | Mass Variance | 5gal Cans Req.
Tacoma 6cyl 17 | 59 Gal | 354 lbs. | Reference | reference
Suzuki Sidekick 22 | 45 Gal | 270 lbs. | -84 lbs | -3
Tacoma 4cyl 18 | 56 Gal | 336 lbs. | -18 lbs | -1
Tundra V8 15 | 67 Gal | 402 lbs. | 48 lbs | +2
Land Cruiser 13 | 77 Gal | 462 lbs. | 108 lbs | +4
Discovery II 13 | 77 Gal | 462 lbs. | 108 lbs | +4
Hummer H2 8.5 | 118 Gal | 706 lbs. | 352 lbs | +12


Payload Comparison (lbs.):

Vehicle | Payload | Fuel as a % of payload | Payload Remainder
Tacoma 6cyl | 1,585 | 22% | 1,231
Suzuki Sidekick | 898 | 30% | 628
Tacoma 4cyl | 1,630 | 21% | 1,294
Tundra V8 | 1,525 | 26% | 1,123
Land Cruiser | 1,470 | 31% | 1,008
Discovery II | 1,600 | 29% | 1,138
Hummer H2 | 2,200 | 32% | 1,494


General Conclusions:
- Available payload is a must greater factor than MPG in this study, unless fuel cost, or environmental impact is considered. For example, the H2 Hummer uses nearly 40% more fuel than any other vehicles in the study, but it also has the highest Payload Remainder.
- The vehicles at the two extremes (Hummer and Sidekick) both had fuel payloads over 30% of available payload capacity
- The Tacoma proved to be the most frugal selection, using much less fuel, while still having a high Payload Remainder.
- The Discover II also did well in the Payload Remainder, but suffers from poor economy based on the size of the vehicle.

So how does a sportsmobile stack up... They have a big gas tank, diesel, and hella payload in the 1 ton...

[The BN Guy]

Could not find any payload capacities other taan cu.ft. for the Xterra and Pathfinder.

Here's what I found...

Vehicle EPA (City) | Total Gallons | Fuel Mass | Mass Variance | 5gal Cans

Frontier 15 | 67 Gal | 402 lbs. | 48 lbs. | +2
Pathfinder | 15 | 67 Gal. | 402 lbs. | +2
Xterra 16 | 62.5 Gal. | 375 lbs. | 31 lbs. | +3

Payload Comparison (lbs.):

Vehicle | Payload | Fuel as a % of payload | Payload Remainder
Frontier|1482| 27% | 1080
Pathfinder N/A----------
Xterra N/A-----------


I'm quite bummed about the inability to compare the X and Pathy! But good to see how the Frontier performed. Now I have a 2000 and those numbers are not available but I figure my mileage is a little lower - more along the lines of 'Cruiser considering the mod's I've made.

[+ d]

Here's where my Grand Cherokee stacks up...not great i suppose, but she'll have to do!


Vehicle | EPA (City) | Total Gallons | Fuel Mass | Mass Variance | 5gal Cans
Jeep Grand Cherokee (WJ - 4.0L) | 15 | 66.6 Gal | 400 lbs. | 46 lbs. | +2


Vehicle | Payload | Fuel as a % of payload | Payload Remainder
Jeep Grand Cherokee (WJ - 4.0L) |1430| 28% | 1030

[The BN Guy]

Hey +, what about the old Cherokee's?

[Scott Brady]

Here's where my Grand Cherokee stacks up...not great i suppose, but she'll have to do!


Vehicle | EPA (City) | Total Gallons | Fuel Mass | Mass Variance | 5gal Cans
Jeep Grand Cherokee (WJ - 4.0L) | 15 | 66.6 Gal | 400 lbs. | 46 lbs. | +2


Vehicle | Payload | Fuel as a % of payload | Payload Remainder
Jeep Grand Cherokee (WJ - 4.0L) |1430| 28% | 1030

That really isnt bad for an SUV. Better than most actually :)

[Life_in_4Lo]

Interesting statistics :lurk:

One thing I thought of whilst going down the chart was possibly the addition of useable cargo area (cu. in of cargo space and actual useable space).

For example, I have seen the inside of the H2 and it is tiny in relation to the sheer mass of it. Plus, the proportionally low roof makes for very little actual useable space.

The H3 is even worse in this regard, although the size is more realistic. Also the side windows are so small, you can barely fit your arm through the window and see. Cool in a hot rod, not so cool in a suv...

I have found pure numbers for interior cu. in. dimensions/capacity very misleading. In real life use, 1" can feel like 1 mile and the shape of the space can determine how useful it is as well.

Anyway, hope that adds something... hehe