Congrats for the lupo 3L
I searched a lupo 3L or a A2 3L but they are rare and the ones I found were more expensive. Since I decided to go for a second hand Prius (because it has been conceived to emit very few pollutants) when the bank account will permit.
You can decide to put money to ecomod it not because it will pay back, but because you are saving money compared to the previous car. I "heavily" aero-modded (not as much as basjoos of course) my car but I consider the aero-mods only contribute to 20% of my saving, vs 80% for my driving, so my aero-mods doesn't deserve the time I spent on them.
Now the aero-mods on my car, and the fact my car is ugly, permit to people to wonder about their own consumption and if 10% of these people save 10% of their fuel then they will save more than if I can save myself, even by stopping all energy consumption.
Now several aero-mods have been done to have fun, while building them and while driving. I do love when a mod change the behavior of the car and I have to change the way I'm driving, per example the rear wheel skirts and pumping up the tires at max-sidewall. The car is now much more fun to drive
Denis.