The RLX's pre-crash front seatbelts will tighten automatically in the event the vehicle detects an impending crash, improving protection against injury significantly. The XTS doesn't offer pre-crash pretensioners.

Both the RLX and the XTS have standard driver and passenger frontal airbags, front side-impact airbags, driver knee airbags, side-impact head airbags, front seatbelt pretensioners, front wheel drive, height-adjustable front shoulder belts, plastic fuel tanks, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, daytime running lights, rearview cameras and available around view monitors.

The National Highway Traffic Safety Administration does 35 MPH front crash tests on new vehicles. In this test, results indicate that the Acura RLX is safer than the Cadillac XTS:

New test not comparable to pre-2011 test results. More stars = Better. Lower test results = Better.

The National Highway Traffic Safety Administration does side impact tests on new vehicles. In this test, which crashes the vehicle into a flat barrier at 38.5 MPH and into a post at 20 MPH, results indicate that the Acura RLX is safer than the Cadillac XTS:

New test not comparable to pre-2011 test results. More stars = Better. Lower test results = Better.

For its top level performance in all IIHS frontal, side, rear impact and roof-crush tests, its standard front crash prevention system, and its headlight's “Acceptable” rating, the Insurance Institute for Highway Safety grants the RLX the rating of “Top Pick” for 2018, a rating granted to only 119 vehicles tested by the IIHS. The XTS has not been fully tested, yet.

The engines in the RLX have a single overhead cam for simplicity. The engines in the XTS have dual overhead cams, which add to the number of moving parts and the complexity of the cylinder heads.

From surveys of all its subscribers, Consumer Reports' December 2018 Auto Issue reports that Acura vehicles are more reliable than Cadillac vehicles. Consumer Reports ranks Acura 15 places higher in reliability than Cadillac.

The RLX's standard 3.5 SOHC V6 produces 6 more horsepower (310 vs. 304) and 8 lbs.-ft. more torque (272 vs. 264) than the XTS' standard 3.6 DOHC V6.

On the EPA test cycle the RLX Sport Hybrid SMG gets better fuel mileage than the XTS AWD (28 city/29 hwy vs. 17 city/26 hwy).

On the EPA test cycle the RLX FWD V6 gets better fuel mileage than the XTS FWD with its standard engine (20 city/29 hwy vs. 19 city/28 hwy).

An engine control system that can shut down half of the engine's cylinders helps improve the RLX's fuel efficiency. The XTS doesn't offer a system that can shut down part of the engine.

Regenerative brakes improve the RLX Sport Hybrid's fuel efficiency by converting inertia back into energy instead of wasting it. The XTS doesn't offer a regenerative braking system.

In heavy traffic or at stoplights the RLX Sport Hybrid's engine automatically turns off when the vehicle is stopped, saving fuel and reducing pollution. The engine is automatically restarted when the driver gets ready to move again. (Start/Stop isn't accounted in present EPA fuel mileage tests.) The XTS doesn't offer an automatic engine start/stop system.

To lower fuel costs and make buying fuel easier, the Acura RLX uses regular unleaded gasoline (premium recommended for maximum performance). The XTS V-Sport requires premium, which can cost 20 to 55 cents more per gallon.

A ten-speed automatic is standard on the Acura RLX, for better acceleration and lower engine speed on the highway. Only a six-speed automatic is available for the XTS.

The RLX offers a standard sequential manual gearbox (SMG). With no clutch pedal to worry about and a fully automatic mode, an SMG is much more efficient than a conventional automatic but just as easy to drive. The XTS doesn't offer an SMG or a conventional manual transmission.

The RLX stops much shorter than the XTS:

The RLX's tires provide better handling because they have a lower 40 series profile (height to width ratio) that provides a stiffer sidewall than the XTS' standard 45 series tires.

The RLX has standard front and rear stabilizer bars, which help keep the RLX flat and controlled during cornering. The XTS' suspension doesn't offer a rear stabilizer bar.

For better handling and stability, the track (width between the wheels) on the RLX is 2.6 inches wider in the front and 2.2 inches wider in the rear than on the XTS.

The RLX handles at .84 G's, while the XTS AWD pulls only .79 G's of cornering force in a Car and Driver skidpad test.

The RLX executes Motor Trend's “Figure Eight” maneuver quicker than the XTS AWD (26.8 seconds @ .67 average G's vs. 27.6 seconds @ .63 average G's).

The RLX has .2 inches more front legroom, .8 inches more front hip room, 1.7 inches more front shoulder room, .2 inches more rear hip room and .7 inches more rear shoulder room than the XTS.

If the windows are left open on the RLX the driver can close them all at the outside door handle. On a hot day the driver can lower the windows at the outside door handle or from a distance using the keyless remote. The driver of the XTS can only close the windows from inside the vehicle, with the ignition on.

The RLX has a standard locking fuel door with a remote release located convenient to the driver. A locking fuel door helps prevent vandalism, such as sugar in the tank and fuel theft. The XTS doesn't offer a locking fuel door.

The RLX's rain-sensitive wipers adjust their speed and turn on and off automatically based on the amount of rainfall on the windshield. This allows the driver to concentrate on driving without constantly adjusting the wipers. The XTS' standard manually variable intermittent wipers have to be constantly adjusted.

Motor Trend performed a comparison test in its July 2013 issue and the Acura RLX won out over the Cadillac XTS AWD.