Money retrained means nothing when cheap oil is gone. Cars are only a thing because we have volumes and energy for large supply chains and scale. A rich person can afford a model-T level car, but large parts of what makes a luxury car are things that they won't be able to get at any price without modern industry that is built on distributed wealth for many people. All the electronics - needs industry. Precision manufacturing - depends on precision electronics. You can't even rebuild a current design if someone thinks to print out the blueprints.
Of course who knows how to end of oil will happen. Best case is a switch to renewables (or fission...) in which case there will be more than enough expensive oil for a few rich people to drive expensive gas cars if they want to. There are lots of other options as well, only time will tell.
(and a nod here to the replies who suggest this was never actually said)
Petromonarchies invest a lot into alternative asset classes: semiconductor industry, logistics and shipping, power electric machines, biomedical development, etc. Renewables are in the list, too.
Most of those are things that depend on cheap energy [mostly oil] today. Only renewables do not, and it is questionable if we will transition fast enough to not collapse society for lack of energy (though this is looking good)