For 2010, the Toyota Tundra gets a new, smaller engine. That's actually good news, because the slightly smaller 4.6-liter V-8 replaces the aging 4.7, making more power and more torque and using less gas in the process. This new engine is complemented by a six-speed transmission, which has an unusually low first-gear ratio and a reasonably tall sixth gear for easy cruising.

The new 4.6-liter engine is rated at 310 horsepower, developing 327 pound-feet of torque at 3400 rpm. With the new engine, the Tundra's fuel economy is 13 city/18 highway (4WD) and 15/20 (RWD). These numbers compare favorably with the outgoing 4.7 V-8's ratings of 13/16 (4WD) and 14/17 (RWD) and 276 horsepower with 313 pound-feet of torque. Both engines make peak torque at 3400 rpm, but the 4.6 revs about 200 rpm higher to hit peak horsepower. Still, it seems clear the new V-8 will be a welcome upgrade from the 4.7, which has been around almost 10 years now. Switching from a cast-iron block to aluminum helped reduce weight, shedding about 65 pounds compared with the outgoing 4.7-liter.

Toyota has achieved these improve-ments by applying technology developed for the optional powerplant, the 5.7-liter V-8. That includes addition of dual VVT-i, which can electronically control intake and exhaust valve timing for optimized performance at low and higher rpm. Dual VVT-i also provides timing flexibility that allows for a cleaner-burning engine, which in turn translates into mileage efficiency. Compression has been increased slightly for more power, and with a shorter stroke, the 4.6 revs a little better than the old 4.7. Another state-of-the-art feature in the 4.6 is water-cooled exhaust gas recirculation, which helps regulate combustion temperatures to keep the catalytic converter working more efficiently. It's primarily an emissions strategy, but it does save a bit of fuel in the process, especially when the engine is operating at light throttle.

We noticed a few changes in the 2010 Tundra SR5 we tested, but they're not conspicuous. The 2010 grille has one fewer bar and the remaining bars are thicker, and the front valance has also been changed. From the rear, the taillight cluster looks a little more modern. The headlights are now manually adjustable in five steps, and stereos have been upgraded.

SIX-SPEED AUTOMATIC
Even with the new engine, we think the most significant addition for 2010 is the six-speed automatic. With a six-speed like this, any engine will work better. It's not the same six-speed Toyota uses with the 5.7; this one, known internally as the A-760, has more in common with the existing five-speed Toyota has long used behind the 4.7. The new six-speed has all the same gears as the old five-speed, but also adds one more ratio, a very tall sixth gear. In essence, the new transmission allows for more efficient cruising for much better highway mileage.

Like just about every modern Toyota transmission we've tested, the new six-speed downshifts readily when called upon, so much so that we can practically select ratios with our throttle foot. There is a manual shift option, should that be your preference, when you want to kick down from overdrive as you go up a steep hill. But our experience was that the six-speed generally anticipated our request for a downshift, giving us what we needed when we needed it. At the track, it clicked through gears readily under full throttle, shifting at about 5500 rpm, just short of the 5900-rpm redline. Full-power starts did produce a slight bog off the line as automatic traction devices kicked in. There would be a quick chirp, very brief hesitation, then the truck would move out strongly, with the engine really catching fire around 3300 rpm. After some experimentation, we found we could move out a little better by disabling the traction control.

Around town, throttle response is strong off the line, even a bit touchy until you get used to it, but the Tundra gets going with ease and seems nimble. It's also notable that the Tundra steers and handles with unusual precision for a full-size pickup, employing rack-and-pinion steering. It parks easily--although shorter folks may find the tall hood a little hard to see over.