It's not new. The CO2 emissions have become inevitable since a good decade now. I remember, back in 2009, I was really close to buy a new Subaru Legacy wagon. The basic 2.0R version, with an automatic gearbox, because I was bored of manuals. But the CO2 emissions jumped from ca. 177 grams (manual) to ca. 205 grams (automatic), and IIRC that meant an extra tax bracket to pay.

Plus the gearbox was only an old 4-speed. So didn't buy the car. And six months later, the new Legacy was launched, and it had become incredibly ugly. And it came with a CVT. So I regretted my choice for a while.

These days, the flemish region has changed its yearly road tax system. It's now based on CO2 emissions, fuel type and Euro certification. Wallonia and Brussels still use the old system based on engine capacity and horsepower, but they'll probably change it sooner or later.