I think this doesn't mean what you think it does. To quote a french reddit user -
It comes from a well known French expression.
"Nous en France on a pas de pétrole mais on a des idées !"
Said by our then-president during the petrol crisis of the 70s. Not sure if it translate well in English.
"We have no petrol but we have ideas" - it's a saying that means basically we have the ability but not the resources.
So when Wenger is saying we have petrol +ideas, he's we're fantastic because we have the resources and the brilliance of Pep.
He is bringing up our resources but I think the use of petrol is just from the french expression, not a comment on the source of our wealth.