Compare the2022 Audi A3VS 2021 Mercedes A-Class

Both the A3 and A-Class have child safety locks to prevent children from opening the rear doors. The A3 has power child safety locks, allowing the driver to activate and deactivate them from the driver's seat and to know when they're engaged. The A-Class’ child locks have to be individually engaged at each rear door with a manual switch. The driver can’t know the status of the locks without opening the doors and checking them.

The A3’s standard lane departure warning system alerts a temporarily inattentive driver when the vehicle begins to leave its lane and gently nudges the vehicle back towards its lane. A lane departure warning system costs extra on the A-Class.

To help make backing out of a parking space safer, the A3’s optional rear cross-path warning system uses sensors in the rear bumper to alert the driver to vehicles approaching from the side, helping the driver avoid collisions. The A-Class doesn’t offer a cross-path warning system.

Both the A3 and the A-Class have standard driver and passenger frontal airbags, front side-impact airbags, side-impact head airbags, front-wheel drive, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, daytime running lights, rearview cameras, available all-wheel drive, blind spot warning systems and rear parking sensors.

The A3’s corrosion warranty is 7 years longer than the A-Class’ (12 vs. 5 years).

The Audi A3’s engine uses a cast iron block for durability, while the A-Class’ engine uses an aluminum block. Aluminum engine blocks are much more prone to warp and crack at high temperatures than cast iron.

From surveys of all its subscribers, Consumer Reports’ January 2021 Auto Issue reports that Audi vehicles are more reliable than Mercedes vehicles. Consumer Reports ranks Audi 6 places higher in reliability than Mercedes.

The A3’s 2.0 turbo 4-cylinder hybrid produces 13 more horsepower (201 vs. 188) than the A-Class’ 2.0 turbo 4-cylinder.

On the EPA test cycle the A3 gets better mileage than the A-Class:

Regenerative brakes improve the A3’s fuel efficiency by converting inertia back into energy instead of wasting it. The A-Class doesn’t offer a regenerative braking system.

To lower fuel costs and make buying fuel easier, the Audi A3 uses regular unleaded gasoline (premium recommended for maximum performance). The A-Class requires premium, which can cost 20 to 55 cents more per gallon.

The A3 Quattro’s standard fuel tank has a gallon more fuel capacity than the A-Class (14.5 vs. 13.5 gallons).

In its Green Vehicle Guide, the U.S. Environmental Protection Agency (EPA) rates the Audi A3 higher (7 out of 10) than the Mercedes A-Class (5). This means the A3 produces up to 8 pounds less smog-producing pollutants than the A-Class every 15,000 miles.

For better traction, the A3 has larger tires than the A-Class (225/45R17 vs. 205/55R17).

The A3’s standard tires provide better handling because they have a lower 45 series profile (height to width ratio) that provides a stiffer sidewall than the A-Class’ standard 55 series tires.

The A3 Sedan has a much larger trunk than the A-Class (11 vs. 8.6 cubic feet).