The RDX is powered by Acura's first turbocharged gasoline engine. The 2.3-liter straight-4 K23A1 engine has all-aluminum construction, an i-VTEC head, and dual balance shafts. It is also one of the first and only four-cylinder powered luxury SUVs. Acura's variable flow turbocharger reduces turbo lag by using a valve to narrow the exhaust passage at low rpm, increasing the velocity of the exhaust flow and keeping the turbine spinning rapidly. At higher rpm, the valve opens to allow more exhaust flow for increased boost. The engine also features a top-mounted intercooler which receives air from the grille, channeled by ducting under the hood. The Acura RDX engine is rated at 240bhp (179.0kW; 243.3PS) at 6000 rpm with a torque peak of 260ft·lbf (350N·m) at 4500 rpm. The U.S. Environmental Protection Agency (EPA) estimated fuel mileage is 19mpg-US (12L/100km; 23mpg-imp) city and 23mpg-US (10L/100km; 28mpg-imp) highway miles per gallon. New more realistic EPA mileage estimates as of February 2007 are 17mpg-US (14L/100km; 20mpg-imp) city and 22mpg-US (11L/100km; 26mpg-imp) highway. The recommended fuel is premium 91 octane unleaded.
The Acura RDX comes standard with a five-speed automatic transmission with Acura's SportShift sequential manual shift capability, activated by paddles mounted on the steering wheel. The paddles can be used in Drive (D) to make a gear change with the transmission returning to automatic mode as soon as the vehicle resumes a steady-cruise state. The Sport (S) setting has higher shift points and quicker downshifts, and using a paddle in “Sport” immediately puts the transmission in full manual mode. The RDX also has a version of Acura's Super Handling All-Wheel Drive (SH-AWD), first seen on the flagship RL sedan. The system can vary the front/rear torque distribution from 90/10 to 30/70, depending on whether the vehicle is accelerating, cruising, hill climbing, taking a curve, or encountering poor road conditions. When taking a curve, a pair of magnetic flux clutches in the rear differential can transfer as much as 100% of the available rear torque to the outside wheel. That torque transfer, combined with a 1.7% rear over-rotation of the rear wheel helps rotate the RDX through a turn.