Both the C-Class Sedan and the A5 have standard driver and passenger frontal airbags, front side-impact airbags, driver knee airbags, front seat center airbag, side-impact head airbags, front seatbelt pretensioners, height adjustable front shoulder belts, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, post-collision automatic braking systems, daytime running lights, blind spot warning systems, rearview cameras, rear cross-path warning, driver alert monitors, available all wheel drive, lane departure warning systems and around view monitors.

Side impacts caused 23% of all road fatalities in 2018, down from 29% in 2003, when the Insurance Institute for Highway Safety introduced its side barrier test. In order to continue improving vehicle safety, the IIHS has started using a more severe side impact test: 37 MPH (up from 31 MPH), with a 4180-pound barrier (up from 3300 pounds). The results of this newly developed test demonstrates that the Mercedes C-Class Sedan is safer than the A5:

There are over 25 percent more Mercedes dealers than there are Audi dealers, which makes it easier should you ever need service under the C-Class Sedan's warranty.

J.D. Power and Associates' 2025 Initial Quality Study of new car owners surveyed provide the statistics that show that Mercedes vehicles are better in initial quality than Audi vehicles. With 59 fewer problems per 100 vehicles, JD Power ranks Mercedes higher than Audi.

J.D. Power and Associates' 2025 survey of the owners of three-year-old vehicles provides the long-term dependability statistics that show that Mercedes vehicles are more reliable than Audi With 30 fewer problems per 100 vehicles in the first three years of ownership, J.D. Power ranks Mercedes higher than Audi.

On the EPA test cycle the C-Class Sedan gets better mileage than the A5:

The C-Class Sedan has 2.9 gallons more fuel capacity than the A5 (17.4 vs. 14.5 gallons), for longer range between fill-ups.

In its Green Vehicle Guide, the U.S. Environmental Protection Agency (EPA) rates the Mercedes C-Class Sedan higher (7 out of 10) than the Audi A5 (4). This means the C-Class Sedan produces up to 13.2 pounds less smog-producing pollutants than the A5 every 15,000 miles.

A nine-speed automatic is standard on the Mercedes C-Class Sedan, for better acceleration and lower engine speed on the highway. Only a seven-speed automatic is available for the A5.

For better traction and acceleration, the C-Class Sedan has larger standard rear tires than the A5 (245/40R18 vs. 235/45R18). The C-Class Sedan's optional rear tires are larger than the largest rear tires available on the A5 (255/35R19 vs. 245/40R19).

The C-Class Sedan's standard 245/40R18 rear tires provide better handling because they have a lower 40 series profile (height to width ratio) that provides a stiffer sidewall than the A5's standard 45 series tires. The C-Class Sedan's optional 255/35R19 rear tires have a lower 35 series profile than the A5's optional 40 series tires.

The C-Class Sedan's drift compensation steering can automatically compensate for road conditions which would cause the vehicle to drift from side to side, helping the driver to keep the vehicle straight more easily. The A5 doesn't offer drift compensation steering.

For better maneuverability, the C-Class Sedan's turning circle is 2.1 feet tighter than the A5's (37.6 feet vs. 39.7 feet).

The Mercedes C-Class Sedan may be more efficient, handle and accelerate better because it weighs about 150 to 250 pounds less than the Audi A5.

The C-Class Sedan is 3.1 inches shorter than the A5, making the C-Class Sedan easier to handle, maneuver and park in tight spaces.

The design of the Mercedes C-Class Sedan amounts to more than styling. The C-Class Sedan has an aerodynamic coefficient of drag of .24 Cd. That is significantly lower than the A5 (.3) and many sports cars. A more efficient exterior helps keep the interior quieter and helps the C-Class Sedan get better fuel mileage.

The C-Class Sedan has .4 inches more front legroom, .3 inches more rear headroom and .5 inches more rear shoulder room than the A5.

Pressing a switch automatically lowers the C-Class Sedan's rear seats, to make changing between passengers and cargo easier. The A5 doesn't offer automatic folding seats.

With its sedan body style, valet key, locking rear seatbacks and remote trunk release lockout, the C-Class offers cargo security. The A5's hatchback body style and non-lockable folding seat defeat cargo security.

Unlike the driver-only memory seat and mirrors in the A5, the C-Class Sedan has standard driver and passenger memory, so that when drivers switch, the memory setting adjusts the driver's seat, steering wheel position and outside mirror angle and the front passenger seat also adjusts to the new passenger's preset preferences.

Heated windshield washer nozzles are optional on the C-Class Sedan to prevent washer fluid and nozzles from freezing and help continue to keep the windshield clear in sub-freezing temperatures. The A5 doesn't offer heated windshield washer nozzles.

To help drivers avoid possible obstacles, the C-Class Sedan offers optional cornering lights to illuminate around corners when the turn signals are activated. The A5 doesn't offer cornering lights. The C-Class Sedan also offers optional adaptive headlights to illuminate around corners automatically by reading vehicle speed and steering wheel angle.

A power rear sunshade and manual rear side window sunshades are standard in the C-Class Sedan to help block heat and glare for the rear passengers. The A5 doesn't offer a rear sunshade.

The C-Class Sedan has a 115-volt a/c outlet on the center console, allowing you to recharge a laptop or run small household appliances without special adapters that can break or get misplaced. The A5 doesn't offer a house-current electrical outlet.

The C-Class Sedan is available in both rear-wheel drive and all-wheel drive configurations. The A5 doesn't offer a two-wheel drive configuration.

The Mercedes C-Class outsold the Audi A5/S5/RS 5 by 56% during 2024.