Here are the key differences between the Mazda 6 and the Volkswagen Passat:

1. Design and Styling
Mazda 6: This car is known for its sleek and sporty design, which features Mazda's "Kodo" design language, including a more aggressive front grille and sculpted body lines.
Volkswagen Passat: This model has a more conservative and understated design, characterized by clean lines and a more traditional sedan appearance.

2. Performance and Engine Options
Mazda 6:
Offers a choice of two engines: a 2.5-liter naturally aspirated inline-4 and a turbocharged 2.5-liter inline-4.
Emphasizes a sporty driving experience with responsive handling and a more engaging ride.
Volkswagen Passat:
Typically equipped with a 2.0-liter turbocharged inline-4 engine.
Focuses more on comfort and smooth driving with less emphasis on sporty dynamics.

3. Interior and Comfort
Mazda 6:
Features a driver-focused cockpit with premium materials.
Offers a more upscale feel with options like Nappa leather and real wood trim in higher trims.
Volkswagen Passat:
Provides a spacious and practical interior with a focus on passenger comfort and legroom.
Uses high-quality materials but has a more conservative design compared to the Mazda 6.

4. Technology and Infotainment
Mazda 6:
Comes with a Mazda Connect infotainment system featuring an 8-inch display, Apple CarPlay, and Android Auto.
Higher trims offer advanced features like a head-up display and premium audio systems.
Volkswagen Passat:
Equipped with the Volkswagen Car-Net infotainment system, it also features Apple CarPlay and Android Auto.
Typically includes a larger touchscreen display and offers features like a digital cockpit in higher trims.

5. Safety Features
Mazda 6:
Mazda's i-Activsense safety suite includes features like adaptive cruise control, lane-keeping assist, and blind-spot monitoring.
Volkswagen Passat:
It comes with a comprehensive suite of safety features, including adaptive cruise control, blind-spot monitoring, and forward collision warning with autonomous emergency braking.

6. Driving Dynamics
Mazda 6:
Known for its sporty handling and driving dynamics, providing a more engaging driving experience.
Features G-Vectoring Control Plus for improved handling and stability.
Volkswagen Passat:
Offers a more relaxed and comfortable driving experience, focusing on ride comfort and ease of driving.

7. Price and Value
Mazda 6:
Generally priced competitively within its segment, offering good value for its sporty characteristics and premium features.
Volkswagen Passat:
Also competitively priced, often appealing to those seeking a more traditional, comfortable sedan with a focus on practicality.

8. Fuel Efficiency
Mazda 6:
The turbocharged engine offers decent fuel efficiency, providing a balance between performance and economy.
Volkswagen Passat:
Known for its fuel-efficient 2.0-liter turbocharged engine, providing good mileage for a midsize sedan.

Conclusion
The Mazda 6 is ideal for those who prioritize sporty design and driving dynamics, while the Volkswagen Passat is suited for those who value comfort, spaciousness, and a more conservative design. Both offer a range of features and technologies, but their core appeal lies in their distinct approaches to design and driving experience.