Conclusion:
In terms of mileage, count on any of these three averaging between 18-21 mpg under normal driving. The difference will likely come down to how aggressively you drive. It's probably safe to say any of these trucks are capable of delivering a combined 20 mpg. So, with fuel economy being essentially a draw between these three, which one would get our vote? We figured it would only be fair to break it down and 'fess up to what our choice would be if we had to plunk down our paychecks on one of these three. Keep in mind this assessment is only for these trucks as tested. There are multiple variations of each of these trucks, with fancier trim, bigger engines, and so on-not to mention how much the addition of aftermarket components can change the character of these trucks. Truth to be told, we'd probably pop for the X-Runner Tacoma or the SE V-6 Frontier with the six-speed, cost no object. Both of these trucks are class leaders in power, but a base-model comparo is a different ballgame.
The Toyota, though seemingly just above average on paper, comes across much better in the flesh. The engine wasn't the most powerful, but it was entirely sufficient to get the job done. Clashing colors and textures not withstanding, the interior fit and finish is typically Toyota top-notch, and the whole truck feels carefully assembled and sturdy enough to take on a weekend romp, get hosed off, and transition seamlessly into commuter duty on Monday.
The Nissan, despite being the least powerful, was the most fun to drive. The ride and handling, for a base stripper, was surprisingly taut and controlled. The body structure was rock-solid, and we didn't hear one squeak or rattle the entire time we had it. The interior fit, finish, and design, though not quite as elegant and polished as the Toyota, is very practical and user-friendly in a utilitarian way. The only major shortcoming, not surprisingly, was the engine power. Even the rev-happy demeanor of the engine wasn't a turn-off, just the lack of relative output. Another 20-25 hp and lb-ft would do a lot to push the base Frontier to the top of its class. A slightly more powerful engine might actually improve fuel efficiency as well, not having to work as hard as the slightly overtaxed (in this application) QR25.
The Isuzu, though a competent truck overall, is not in the same league as the Toyota or Nissan from an overall refinement and quality standpoint. The flat, hard plastic dashboard, though not particularly appealing from an aesthetic standpoint, might make the best texture to paint for doing a custom interior treatment. The engine and powertrain, other than the mismatched gear ratios, is competitive and the class leader in power and economy. Thanks to its sharp styling, it may be the most promising candidate for customization and aftermarket upgrades. Probably the most compelling reason to pick the Isuzu is the warranty. At 7 years and 75,000 miles, the powertrain warranty and 3-year, 50,000-mile basic warranty is better than Chevy and GMC's 5/60 powertrain and 3/36 basic coverage.
Overall, for the best all-around four-cylinder truck package off the showroom floor, we'd have to give the nod to the Tacoma. Despite what the sales brochures might say, none of the engines in this test could be truly described as "powerful." If you're looking for power, just simply step up and get the V-6 option, otherwise you'll be unhappy. But, the Toyota's engine provided ample power for a commuter and returned respectable fuel economy. The build quality and fit and finish meet Toyota's typically high standards. In terms of driving dynamics, it drives like what it is-a truck. It doesn't have the zippy, sporty feel of the Nissan, but its dynamics are entirely appropriate for a truck, especially considering the off-road-oriented suspension of the PreRunner. Toyota has enjoyed a long-running status as segment leader in compact trucks, and with the latest version of the Tacoma, even in four-cylinder form, it retains its crown. Although, the Nissan, with just a tad more power, would be a real contender for the econo-truck throne.