April 2008
How we test trucks
CR’s special checks for brutes and utes
Every vehicle we rate has to undergo an extensive battery of on-road tests. But when it comes to more heavy-duty vehicles,
particularly SUVs and pickup trucks, we add tests and take measurements appropriate to their special qualities. Those include
towing capabilities and cargo volume for some, off-roading and rock-climbing for others, and third-row accommodations, if
available.
The process really starts with the options we select when we buy our test vehicles in the first place. We usually equip them with the most popular trims and options consumers find at dealerships, but always add a towing package. We make sure that all the vehicles in a test group are as closely matched as possible.
HITTING THE TRAIL
We have an off-road course at our Connecticut test center that consists of a winding, sloping, rutted trail through the woods
complete with boggy sections and half-buried logs and stumps. But the trail changes with rainfall and erosion. It can even
change in a single day, as muddy ruts grow deeper or sloppier or finally expose the underlying gravel. That makes it hard
to repeat the test conditions exactly.
So we regard these trail trials as informal tests and don't use our observations in calculating a vehicle's overall score. However, these trials do tell us something about an all-wheel-drive vehicle's four-wheel traction. These tests have established, for instance, that tires with an aggressive off-road-type tread pattern have an edge here, but those same tires tend to do less well in dry and wet-pavement braking, and they're noisier.
CLIMBING THE ROCKS
We use a special rock-hill climbing test for vehicles that have four-wheel drive and low-range gearing, and for some lacking
low-range that are advertised as off-road ready.
The rock hill has a 23-degree slope constructed of large boulders held in place with concrete. Although this course is only 70 feet long, it can pose a real challenge.
We score performance here, but since most vehicles never go off road and those that do do so only rarely, the numbers we assign don't affect a vehicle's official overall score.
David Champion, director of the Auto Test Center, explains:
"We can learn a lot from the rock hill. Take throttle modulation. With some trucks you can set a steady pace and keep it for the duration. With others you're constantly putting your foot on or taking it off the gas as the truck lurches from boulder to boulder. We gain first hand knowledge about effective ground clearance and axle articulation, especially if the truck crashes and bangs on its way up the hill. Then there's the ride: Some trucks are commendably composed while others bounce violently. We know, too, that running boards can be especially vulnerable. Our last Toyota Tundra was a superb climber, but the rock hill threatened to turn its running boards into metal sculpture."
PULLING THE WEIGHT
Our trucks, SUVs and minivans are equipped with towing gear from the manufacturer. Most of our towing tests use the same four-wheel cargo trailer, weighted to either 3,500 or 5,000 pounds. We also have a 7,500-pound rig we use for heavy-duty vehicles, such as the 2500-series pickups we tested in 2007.
When we test a group of similar SUVs or trucks, we key the load to the vehicle with the lowest (lightest) rated towing capacity. Then all the vehicles in the test group are tested using the same load weight.
The main towing tests are straight-forward 0- to 60-mph sprints. We conduct them on the same level straightaway we use for other acceleration tests. Most modern vehicles can climb up to 60 mph, unloaded, in around 10 seconds or less. In our towing tests, typical times are about twice what they are when the vehicle is unloaded. As a rough guide, we consider 15 or 16 seconds to be quick, 19 or 20 seconds to be average and 22 to 24 seconds to be slow. We also note how stable the vehicle is when towing.
CARRYING THE LOAD
SUVs have become the modern station wagon, and half the point of owning one is being able to haul loads of stuff. The size
and shape of the rear opening and protrusions into the cargo area can make the difference between a vehicle that can swallow
an armchair or hold a trash can standing upright and one that can't.
For enclosed vehicles such as SUVs and minivans, we have been using an adjustable pipe-frame device we call a MERP, which stands for Maximum Extruded Rectangular Parallelepiped. We first fold down, fold up, tumble, or remove the second and third row seats to make the most space possible without using tools. We adjust the MERP so it just fits through the rear hatch and extends into the cargo bay as far as it will go, while still allowing the hatch door or tailgate to close. Then we measure the volume suggested by the MERP device. That gives us a measure of the largest box that would fit entirely inside the vehicle.
For pickup trucks we measure the length and width of the bed floor and height up to the top of the bed rails. We multiply those dimensions to get a bed-volume measurement.
FILLING THE SEATS
In recent years, three rows of seats has become the norm for all but the small-sized SUVs. Generally, third-row accommodations
in truck-based SUVs are notoriously uncomfortable for adults. You sit near the floor with your knees up, toes cramped, and
head grazing the roof. You may have to adopt humiliating postures to crawl in or out. Minivans and some car-based SUVs can
be much more accommodating.
We judge the third row much like any other seat. We look for ease of access, comfort, and posture. We also note the adequacy of rear head restraints and the ease of installing child seats and boosters. Child-seat LATCH hooks are often hard to use. We've noticed that half-grown children, say 6- to 10-year-olds, seem perfectly at home in the "way back," while older, full-grown people often find the seats claustrophobic.
The process really starts with the options we select when we buy our test vehicles in the first place. We usually equip them with the most popular trims and options consumers find at dealerships, but always add a towing package. We make sure that all the vehicles in a test group are as closely matched as possible.
HITTING THE TRAIL
Our off road course has rutted trails, slopes, and boggy sections.
So we regard these trail trials as informal tests and don't use our observations in calculating a vehicle's overall score. However, these trials do tell us something about an all-wheel-drive vehicle's four-wheel traction. These tests have established, for instance, that tires with an aggressive off-road-type tread pattern have an edge here, but those same tires tend to do less well in dry and wet-pavement braking, and they're noisier.
CLIMBING THE ROCKS
The rock hill has a 23-degree slope constructed of large boulders held in place with concrete. Although this course is only 70 feet long, it can pose a real challenge.
We score performance here, but since most vehicles never go off road and those that do do so only rarely, the numbers we assign don't affect a vehicle's official overall score.
David Champion, director of the Auto Test Center, explains:
"We can learn a lot from the rock hill. Take throttle modulation. With some trucks you can set a steady pace and keep it for the duration. With others you're constantly putting your foot on or taking it off the gas as the truck lurches from boulder to boulder. We gain first hand knowledge about effective ground clearance and axle articulation, especially if the truck crashes and bangs on its way up the hill. Then there's the ride: Some trucks are commendably composed while others bounce violently. We know, too, that running boards can be especially vulnerable. Our last Toyota Tundra was a superb climber, but the rock hill threatened to turn its running boards into metal sculpture."
PULLING THE WEIGHT
Our trucks, SUVs and minivans are equipped with towing gear from the manufacturer. Most of our towing tests use the same four-wheel cargo trailer, weighted to either 3,500 or 5,000 pounds. We also have a 7,500-pound rig we use for heavy-duty vehicles, such as the 2500-series pickups we tested in 2007.
When we test a group of similar SUVs or trucks, we key the load to the vehicle with the lowest (lightest) rated towing capacity. Then all the vehicles in the test group are tested using the same load weight.
The main towing tests are straight-forward 0- to 60-mph sprints. We conduct them on the same level straightaway we use for other acceleration tests. Most modern vehicles can climb up to 60 mph, unloaded, in around 10 seconds or less. In our towing tests, typical times are about twice what they are when the vehicle is unloaded. As a rough guide, we consider 15 or 16 seconds to be quick, 19 or 20 seconds to be average and 22 to 24 seconds to be slow. We also note how stable the vehicle is when towing.
CARRYING THE LOAD
An adjustable pipe-frame box helps us measure cargo capacity.
For enclosed vehicles such as SUVs and minivans, we have been using an adjustable pipe-frame device we call a MERP, which stands for Maximum Extruded Rectangular Parallelepiped. We first fold down, fold up, tumble, or remove the second and third row seats to make the most space possible without using tools. We adjust the MERP so it just fits through the rear hatch and extends into the cargo bay as far as it will go, while still allowing the hatch door or tailgate to close. Then we measure the volume suggested by the MERP device. That gives us a measure of the largest box that would fit entirely inside the vehicle.
For pickup trucks we measure the length and width of the bed floor and height up to the top of the bed rails. We multiply those dimensions to get a bed-volume measurement.
FILLING THE SEATS
Some vehicles with third rows have problems with comfort and access.
We judge the third row much like any other seat. We look for ease of access, comfort, and posture. We also note the adequacy of rear head restraints and the ease of installing child seats and boosters. Child-seat LATCH hooks are often hard to use. We've noticed that half-grown children, say 6- to 10-year-olds, seem perfectly at home in the "way back," while older, full-grown people often find the seats claustrophobic.
