We're frequently asked about how we decide to equip the test vehicles we buy. Since we buy every vehicle we test, we have more control over trim level and equipment than car magazines and Web sites who borrow vehicles from a manufacturer. These press fleets aren't limitless. In many cases, their size has dwindled in recent years as manufacturers look to reduce costs, making it even harder for the media to set up apples-to-apples comparisons. Since car companies want to do well in magazine tests, those press vehicles often have every performance-oriented feature available, are high trim line, and sometimes omit weight-adding options.

Choosing the right pickup truck variation to test is a difficult challenge--one that took a lot of consideration on our part. Pickups are unique in that they offer seemingly millions of combinations of body styles, trims, engines, and axle ratios. According to recent sales patterns, we knew that half-ton crew cab 4x4 trucks in a mid-level trim are the popular choice for most consumers, so we focused on those for our recent test.

Beyond those considerations, when we buy a test vehicle, choosing its equipment requires balancing several goals. The process is complicated since manufacturers don't make "ease of magazine comparison test construction" part of a vehicle's design brief, nor do dealers necessarily stock similar truck packages from brand to brand. In general, we want to test a representative vehicle that is comparable to other vehicles in the test group (and previously tested peer vehicles). We also typically test the version--powertrain and trim level--that most regular consumers will buy. And, even though price is not a factor in our scoring, it's nice to keep the as-tested prices in the same ballpark.

So, based on those principles, we tested a Silverado 2LT with the 5.3-liter V8 and a Tundra SR5 with its 5.7-liter V8. These are the most popular powertrains for the 4x4 crew cab trucks we tested, according to manufacturers' sales data. But given the Tundra's horsepower advantage, we considered testing a Tundra with the smaller 4.7-liter V8 or, on the flip side, a Silverado with the 6.0-liter V8.

The problem is: maintaining parity with the smaller engine in the Tundra would then suggest opting for less-powerful V8 engines in the other trucks. The result would mean a 4.7-liter Dodge, a 4.8-liter Chevy, and a 4.6-liter Ford. That test would be evenly matched in displacement, but given that those engines aren't really bought by most consumers in the crew cab 4x4 trucks we were testing, it wouldn't be very useful.

So what about the 6.0-liter Chevy? This up-level powertrain would have improved acceleration times, but revised 2008 EPA fuel economy estimates show the K1500 4x4 6.0-liter gives up two mpg overall to the 5.3-liter.

Pickup trucks are unique in that you can typically select the rear axle ratio. Again, like most buyers, we stuck with the standard axle ratios. Manufacturers fit these because they are a good all-around compromise of fuel economy and towing capacity. We could have opted for a different axle ratio in the Silverado and the others that would have improved towing capacity and acceleration--but that would have adversely affected fuel economy.

Indeed, when you read advertisements touting the maximum towing capacity claims for most trucks, they are for an optimized combination of body type, drivetrain, and axle ratio--regardless of if anyone buys them that way or if you'd find that configuration at your local dealer. In contrast, the 5.7-liter Tundra Double Cab 4x4 comes in only one configuration, with a relatively aggressive rear axle ratio that helps provide a high standard towing capacity of 10,300 pounds.

Even though the axle ratio subtracts from overall fuel economy, the Tundra boasts the best fuel economy (by a small margin) and the best acceleration (by a big margin) of this group--an impressive feat. GM has done a lot of work to optimize their 5.3-liter pushrod engine, even adding a system that shuts down four cylinders in some conditions, but it can't quite match the combination of the Tundra's overhead-cam engine and six-speed automatic. (For now, the Silverado 1500 has only a four-speed automatic.)

Of course, many choices beyond powertrain and driveline decisions can affect the scoring. When we went to buy a Tundra SR5 with desired equipment (like a power seat), we found that Toyota's limited build configurations meant we couldn't get a Tundra without the TRD suspension package. Given our druthers, we would have avoided the serious off-roading package, as we did on the other trucks. With the Silverado, for example, we bought the Chevy's Z85 towing suspension instead of the stiffer Z71 off-road set-up. That Z85 suspension gave our Silverado a better ride than the Tundra.

To sum up, keep in mind that our Ratings reward well-rounded vehicles. Clearly, we use different scoring criteria for pickup trucks than for other vehicles since pickup truck buyers care about things like payload and towing capacity. But there's more than that; we look at trucks from the point of view of private owners who use the truck to commute during the week and then haul mulch or tow a boat, horse, or other trailer on weekends. Many other factors like fuel economy, acceleration, interior ergonomics, and fit and finish all play a role in daily use. (This is reflected in our top-rated truck, the Chevrolet Avalanche, a truck that tows less and is slower than the Tundra.) In other words, while towing capacity matters, it's certainly not the end-all of the scoring.

To clarify how we set up the pickup truck test (added 8/13):

1) This test was not a comparison of maximum towing capabilities for each truck platform. Towing capacity is just one of many test findings discussed in the report; we perform more than 50 tests on each vehicle. Remember that the Chevrolet Avalanche, which is slower and tows less than the Tundra, handily outscores the Toyota.

2) Even if we picked a Silverado that towed more, either via a different axle ratio or the 6.0-liter engine, it is no guarantee that it would result in a higher Overall Score. We weigh fuel economy more than towing capacity, and either change in the truck's equipment would adversely affect the fuel economy score.

3) Why weigh fuel economy more than towing capacity? Because you have to have gas in the truck every day, but most owners only tow occasionally. At 14-15 mpg overall, another 1-2 mpg matters a lot. (Both EPA and other comparison tests show that the 6.0-liter Silverado gets less economy than the 5.3-liter or the Tundra.) Also, even the 7500-pound towing capacity of the tested Silverado is plenty for most owners.

4) Sure, you can custom-order a truck that is optimized for towing. But we spoke with truck engineers from each of the three domestic competitors before purchasing the trucks. Their insights helped us determine the most representative trucks to test. Note: the take rate for the 6.0-liter in the Silverado 1500 Crew Cab 4x4  is all of 9 percent.

5) The Tundra wasn't optimized for this test because it was the only truck in the test with an off-road suspension. Saddled with the TRD package, the Tundra had a stiff ride that hurt its final score.

6) Our subscriber data, based on millions of vehicles over the years, has shown consistently high reliability for Toyota vehicles. By contrast, even though the first-year reliability of the Tahoe (which shares the Silverado's platform) has been good, year after year the Silverado has been less reliable than the Tahoe.  Because of the Silverado's past below-average performance, we are unable to predict its future reliability, whereas the strong historical performance for both Toyota and Tundra enable us to predict its future performance.

--Tom Mutchler

Read the complete full-sized pickup truck test.
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