Yeah, I suppose that depends on the phrasing of the law, but I read nctnico's post as "enough panels to actually produce >= 1kW at noon during a sunny summer day".
However, even if it's just "installed power", it's still a lot. Even with very good panels (200W/m
2), it would be struggle to find 5m
2 of usable area on the outside of a car. Perhaps if the law allows for foldable/storable system, tilting roof and door panels, or a panel that extends over the windscreen and side windows when parked, you might squeeze out 1kW in perfect conditions.
nctnico, would you mind checking out the regulation and translate wording? My Dutch is a bit rusty.