Acura MDX: Is the 2016 or the 2015 model the best choice?

Even though the current-generation Acura MDX has been on sale for only two model years, significant changes arrive early for the 2016 model year, which is available now. Biggest among them is a shift from a six-speed automatic transmission to a new nine-speed. Based on our experience with an Acura TLX V6 AWD, we're not sure this new transmission is an improvement.

Shift smoothness with the nine-speed in our tested TLX was disappointing, with frequent bumps and indecisiveness at selecting gears. We hope that more time to fine-tune the transmission calibrations for the MDX will bring refinement.

Top-trim MDX Advance models will now come with idle stop, which shuts off the engine to save fuel when the car is stopped. In our TLX, this start-stop system was slow to fire the engine back up when it was time to pull away, eventually launching the car with a sharp jolt when it was finally ready.

The new MDX nine-speed also comes with an electronic shifter, which replaces the conventional shift lever.With the electronic shifter, you select from an array of buttons mounted flat on the console. Doing this by feel alone is very difficult, and we found it easy to confuse the parking brake switch with the one for reverse on our TLX. The TLX was recalled because this shifter could indicate that the car was in Park when it really wasn't.

Significant improvements in fuel economy would help counterbalance these transmission hassles. But both the 2015 and 2016 MDX AWD (without idle stop) are rated at 21 mpg overall by the EPA. Oddly, highway fuel economy dropped from 27 to 26 for the 2016 MDX. More gears sometimes bring acceleration improvements, but then again, the six-speed MDX was no slouch.

On the plus side, the AcuraWatch suite of high-tech safety gear is now available on all MDXs, including the base model without the Technology package. This $1,200 option adds active cruise control, forward-collision warning with automatic braking, and lane-departure mitigation. Other improvements include added equipment, such as Siri capability (Apple), and reduced weight from the lighter transmission and redesigned rear differential.

Other than bragging rights in the "how many gears" contest among luxury brands and the added safety gear, we're scratching our heads to see how the MDX is improved. For now, if you had your heart set on a 2015 MDX, we don't see any good reason to wait for the new one, especially if you can negotiate a more favorable price.

As for Consumer Reports, we'll buy a 2016 Acura MDX to measure exactly what the new transmission brings to this popular luxury SUV.

—Tom Mutchler