Mercedes W202 C250 Turbo - Car upgrade?

Hello.

I currently own an automatic C250 Turbodiesel from 1995.
I love this car, it’s my daily, reliable, is fast when it needs to be and also very comfortable for big journeys.

However there’s one downside which is fuel economy.
Right now I’m averaging a 8.8L/100Km which is a 26.7 MPG in US Gallons.

I’m currently thinking of either exchanging for a W211 E220 CDI or a BMW E46 320d (136 or 150hp version).

What would be your opinion in this “upgrade path”?