Toyota, long known for its ultra-conservative incremental product improvement strategy, is now facing some new competition with the imminent arrival of the 2015 Chevrolet Colorado and GMC Canyon, as well as indications that Nissan is readying a next-generation Frontier. Our spy-photo correspondents got some pics of this Toyota Tacoma mule testing in the desert. Aside from some mismatched trim and a whole lot of sensors and wires, it doesn’t appear to differ significantly from the current Tacoma.

Although this test mule is a manual, it’s expected the four- and five-speed automatics currently offered on the I-4 and V-6 Tacoma models, respectively, will both be replaced by a six-speed automatic, with the motivating factor almost certainly being fuel economy. This model appears to be a V-6 4x4 based on exhaust plumbing. The new GM midsize trucks will have an all direct-injected engine lineup, and while the Tacoma’s current 4.0L V-6 has proven reliable and torquey, it’s no longer the class-leader in terms of either fuel economy or power. There’s a chance the engine could get direct-injection with the next makeover, but knowing Toyota, it will likely stick with the proven port-injection setup as long as it can until regulatory pressures force a change.

The loaded trailer rig suggests that Toyota may raise the towing or payload ratings for the Tacoma in the face of GM’s claimed 7,000-pound rating for the V-6 Colorado and Canyon. The tow rating may increase even more with the introduction of the 2.8L Duramax diesel (the foreign-market Colorado with the diesel has a rating of 7,700 pounds). The current maximum tow rating for the Tacoma is 6,500 pounds for the Double Cab Short Bed V-6. The refreshed Tacoma may roll into showrooms as soon as fall 2015.