There is another kind of truck. They are the full-size truck-based SUVs, such as this 2015 Infiniti QX80. It’s one example of the giant luxury vehicle species that can carry seven or eight people in comfort. These SUVs are also meant to tow relatively heavy loads, although not as much as their pickup truck counterparts. Nonetheless, the 2015 QX80 has a 8,500 lbs maximum towing rating. This allows you to bring a horse trailer or a good-sized boat with you.
When selecting the truck and trailer, always be mindful of the maximum payload rating. For example, if you hitch up a 8,500 pound trailer to the QX80, you will have 762 pounds of payload capacity left over. This is because the trailer needs to be setup to push on the truck with at least 10% of its weight (or 850 pounds in this case). The leftover 762 pounds does not leave much capacity for people and cargo. If you want to bring more than three people and tow around 8,000 lbs, then you need to look at the respective light-duty pickup trucks. The all-new 2016 Nissan Titan is on the horizon and it will have capability to tow around 12,000 lbs.
Raw power and low gearing is needed to tackle an extreme towing test like the Ike Gauntlet. The QX80 delivers the power from the 5.6L V8 with 400 horsepower @ 5,800 rpm and 413 lb-ft of torque @ 4,000 rpm. The 7-speed automatic transmission handles the shifting, but the final drive ratio is an unusually high 2.93. The transmission compensates for this with an extra low 4.88 first and 3.17 second gear ratios. However, can the transmission and rear axle work well together to maintain 60 MPH up this extreme incline?
The horse trailer that used for the previous tests had a brake failure, so we switched to the new 22-foot flat-bed trailer from Load Trail. It’s a gravity assisted tilt trailer with heavy duty 7,000 pound axles. We are using a 1968 Ford Bronco half-cab as ballast, although great looking ballast at that. After we remove Roman from the cabin and leave Nathan and Kent, the overall load is 7,760 pounds (or 10 pounds more than with the Yukon and Navigator).
Altitude Power Loss
We are measuring calculated power loss on this and all Ike Gauntlet runs. We need three variables to get this accomplished: barometric pressure, ambient temperature, and relative humidity. We measure this with a portable weather station near the Eisenhower Tunnel (at the top of this test). This time the data was: 19.76 inHg of pressure, 44F temperature, and low relative humidity at around 30%. The result is a calculated 33% loss of power at the top elevation of the test relative to the standard provided by the SAE (Society of Automotive Engineers). This is applicable to the naturally aspirated engines.
How did it do? Check out the comparison data table here and watch the video at the bottom.
Fullsize SUV – Ike Gauntlet
|2015 Infiniti QX80||2015 GMC Yukon XL||2015 Lincoln Navigator|
|As Tested $||$80,285||$77,925||$73,895|
|Engine||5.6-liter V8||6.2-liter V8||3.5-liter V6|
|Power (hp / lb-ft)||400 / 413||420 / 460||380 / 460|
|Tow Rating||8,500 lbs (2.93 axle)||7,900 lbs (3.23 axle)||8,600 lbs (3.73 axle)|
|Payload Rating||1,612 lbs||1,492 lbs||1,470 lbs|
|Test Load (trailer + ppl)||7,760 lbs||7,750 lbs||7,750 lbs|
|Suspension Sag||1 in||0 in||1.5 in|
|Ambient Temp F||44F||28F||28F|
|Relative Humidity||Low (30%)||Low (25%)||Low (25%)|
|Barometric Pressure (at top)||19.76 inHg||19.76 inHg||19.76 inHg|
|Calculated Power Loss||33 %||33 %||N/A|
|Down: Transmission Temp||normal||normal||normal|
|Up: Transmission Temp||normal||normal||normal|
2015 Infiniti QX80 – Ike Gauntlet extreme towing test.
Andre Smirnov is a life-long automotive enthusiast, writer, reporter, and software engineer. He has been writing and reporting at TFL since 2011.