The 2017 BMW 420 is a stylish and sporty coupe or Gran Coupe (4-door) that offers a good balance of performance, handling, and practicality. It's known for its engaging driving experience, thanks to its well-balanced chassis and responsive steering. The 420d model, in particular, is praised for its diesel engine's strong torque and fuel efficiency. 

Key Features and Performance:
  • Engaging Driving Experience:

    The 4 Series, especially the 420d, is praised for its agility, sharp handling, and responsive steering. 

  • 420d Engine:

    The 2.0-liter diesel engine (420d) delivers 190 horsepower and 400 Nm of torque, providing a good balance of performance and fuel economy. 

  • Practicality:

    The Gran Coupe version offers four doors and a good amount of boot space, making it more practical than the coupe. 

  • Interior:

    The interior is driver-focused with well-placed controls and comfortable seats, though some find the design a bit mature. 

  • Technology:

    The 2017 4 Series received updates including new LED headlights and taillights, updated bumpers, and an updated iDrive infotainment system. 

Potential Drawbacks:
  • Ride:

    Some reviewers found the ride to be firmer than expected, even with the adaptive suspension. 

  • Interior:

    While functional, some find the interior materials and design a bit dated compared to competitors like the Mercedes C-Class. 

  • Engine Noise:

    The diesel engine in the 420d can be a bit noisy, especially at higher speeds. 

Overall:
The 2017 BMW 420, particularly the 420d, is a great choice for those seeking a sporty and engaging coupe or Gran Coupe with a good balance of performance, handling, and practicality. It's a driver's car that also offers a comfortable and refined experience, especially on longer journeys. However, those prioritizing ultimate luxury or a more modern interior design might want to consider other options.