Good subject, and nicely captured.
How are you doing the conversion? I'd like to see a bit more tonal separation between the car, the floor and the wall behind. Unless they are all very close to the same colour, you should be able to get more separation by adjusting the colour conversion. In Lightroom I'd load up the raw file, go into the Develop module, hit "V" to get a basic B&W conversion, then play with each of the colour sliders (under HSL/Color/B&W) to change the tonal effect of each colour. I'd imagine that most conversion software should allow similar adjustments.
Keep up the good work! 🙂