Hi Benny, welcome to EM
Getting less than 5 l/100km in a petrol is quite good
Ecomodding in Germany isn't going to be easy (laws, polizei, etc.), you will probably have to stay with discreet mods (like a warm air intake, grille block, smooth wheel covers, engine block heater, maybe an engine kill switch) and
hypermiling techniques. I still think you can easily get below 4.5 l/100km.
Some cars had an engine undertray fitted only in certain versions, usually with diesel engines. Maybe there is an engine tray that will fit your model? Since it will be certified for your car there shouldn't be any legal problems.
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e·co·mod·ding: the art of turning vehicles into what they should be
What matters is
where you're going, not
how fast.
"... we humans tend to screw up everything that's good enough as it is...or everything that we're attracted to, we love to go and defile it." - Chris Cornell
[Old] Piwoslaw's Peugeot 307sw modding thread