I wouldn’t get too excited about this. The French court basically ruled against it because it wasn’t taxing enough people.
I agree: That's what they did.
However, the purpose of the new tax on automobile fuel was to raise money. And the only way they (the French government) could get this tax passed was to exempt the hundreds of thousands of businesses and the basic industrial producers of their economy from the tax. So, when they have to re-introduce the tax on January 20, Sarkozy must now spread his tax out on a whole LOT of other businesses and groups who will now have to pay.
And they won't like to see THEIR taxes raised, when before (with the fuel surcharge that has been declared illegal) the ones paying are the automobile drivers, farmers, truckers, and taxi drivers. And they have less influence (less money) to influence the government.
He (Sarkozy) now has to pass the tax law again, and now has t face more opposition to the new law from a wider base, and that base has seen the first version defeated.
Momentum can shift, though, as you said, this is not the final tax bill.