For enhanced safety, the front and rear seat shoulder belts of the Audi S4 have pretensioners to tighten the seatbelts and eliminate dangerous slack in the event of a collision and force limiters to limit the pressure the belts will exert on the passengers. The BMW M3 doesn’t offer pretensioners for the rear seat belts.
For enhanced safety, the front seat shoulder belts of the Audi S4 are height-adjustable to accommodate a wide variety of driver and passenger heights. A better fit can prevent injuries and the increased comfort also encourages passengers to buckle up. The BMW M3 doesn’t offer height-adjustable seat belts.
The S4 has all-wheel drive to maximize traction under poor conditions, especially in ice and snow. The M3 doesn’t offer all-wheel drive.
Both the S4 and the M3 have standard driver and passenger frontal airbags, front side-impact airbags, side-impact head airbags, plastic fuel tanks, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, daytime running lights, available crash mitigating brakes, blind spot warning systems and rearview cameras.
J.D. Power and Associates’ 2015 survey of the owners of three-year-old vehicles provides the long-term dependability statistics that show that Audi vehicles are more reliable than BMW vehicles. J.D. Power ranks Audi 14th in reliability, above the industry average. With 8 more problems per 100 vehicles, BMW is ranked 18th.
On the EPA test cycle the S4 Auto gets better fuel mileage than the M3 Auto (18 city/28 hwy vs. 17 city/24 hwy).
For better maneuverability, the S4’s turning circle is 2.3 feet tighter than the M3’s (37.7 feet vs. 40 feet).
The design of the Audi S4 amounts to more than styling. The S4 has an aerodynamic coefficient of drag of .3 Cd. That is significantly lower than the M3 (.34) and many sports cars. A more efficient exterior helps keep the interior quieter and helps the S4 get better fuel mileage.
As tested by AutoWeek while at idle, the interior of the S4 is quieter than the M3 (42 vs. 43 dB).
The S4 has a larger trunk with its rear seat up than the M3 (12.4 vs. 12 cubic feet).
The S4’s front and rear power windows all open or close fully with one touch of the switches, making it more convenient at drive-up windows and toll booths, or when talking with someone outside the car. The M3’s passenger windows don’t open or close automatically.
To keep a safe, consistent following distance, the S4 Prestige offers an optional Adaptive Cruise Control, which alters the speed of the vehicle without driver intervention. This allows the driver to use cruise control more safely without constantly having to disengage it when approaching slower traffic. The M3 doesn’t offer an adaptive cruise control.
Insurance will cost less for the S4 owner. The Complete Car Cost Guide estimates that insurance for the S4 will cost $1375 to $2900 less than the M3 over a five-year period.
Intellichoice estimates that five-year ownership costs (depreciation, financing, insurance, fuel, fees, repairs and maintenance) for the Audi S4 will be $336 to $5848 less than for the BMW M3.
The S4 was selected by Automobile Magazine as their 2010 Car of the Year. The 3 Series was Car of the Year in 2006.