I see the Toyota as the closest to the Frontier. It's comparably sized (moreso than other small trucks) and has a similar powertrain. It's also Japanese, so you can expect better reliablity than it's american counterparts. To me, the Taco and the Frontier are the only small trucks worth a look. The Tacoma stepped up to a 4 liter this year as well. It makes 245 hp and 283 ft lb of torque (compared to the Frontier's published 265 and 284), and is a capable truck. It makes slightly less power, but it's a Toyota, so you know it's well built. Toyota may have lost their touch of late, but you wouldn't know it looking at the Tacoma.
The Mazda B-Series is just a rebadged Ranger, and Rangers are turds at worst, and average at best. You will never be more than moderately happy with anything about the Ranger (I know--I've owned one). It'll get the job done, but that's it. And, being Ford, you can expect a bulletproof yet gutless engine, a terrible transmission, and more electrical problems than you knew a car could have (by the way, the other day, the accelerator pedal FELL OFF my old ranger [I sold it to a friend, so I still see it often]). The Ranger is a 22 year old platform in dire need of update. It's also tiny, especially when compared to the newer (in fact, all BRAND new) competition. The only reason I'd consider it is if I were looking for the least expensive truck I could possibly find--except that the Ford is more expensive...
Dodge's Dakota is far bigger than the Nissan, in size and engine wise, with an available 4.7 liter V8 making 26 more torque than the Frontier. The Dakota is what 1/2 ton trucks were 15 years ago. I like the Dakota. This'd be my #3 choice if I were shopping for trucks. Also, the Dakota will soon (or is already) be available rebadged as the Mitsubishi Raider which is, in my ever-so-humble opinion, ugly as hell. The Dakota has that "real truck" feel that's missing from everything else but the Frontier.
I've heard good things about Chevy's Colorado(GMC Canyon). Unfortunately, the base Inline 5 is a poorly balanced engine and seems to be a major complaint. One thing I've noticed about the Colorado is that the higher end models have a great fit-and-finish to them, while the base models look--cheap. I've never noticed such a range of quality in a single model before. The Linear 6 is a great engine from what I have heard and read. As yet, the V8 from the Trailblazer I've heard many good things about is not available in the Colorado. If you are seriously considering the Colorado/Canyon, also note that this summer (this month I believe) Isuzu will be releasing their rebadged version, the i-Series.
I have the C&D issue with the comparo, but I don't think I'd count on it to help with your buying decision here, as they gave the win to the Honda Ribbedcond--I mean Ridgeline, which is not even a truck, but a monocoque car-based SUV with a bed.When I get back home in a few hours, I'll either scan it or post the important parts.
Meanwhile, I hope this helps a little. I would have included the Isuzu i-Series and the Mitsu Raider, but they were not available choices for the comparison...
Here's another useful website:
http://www.pickuptruck.com
Modified by MinisterofDOOM at 4:56 AM 7/1/2005