We should be far more worried about C02 production than oil depletion. We can make petroleum products out of
coal, and there is plenty of that. However, the problem with making gasoline from coal is that it releases far more C02 into the atmosphere than making gasoline from petroleum does. CO2 emissions are also higher when converting oil shale and sands, another plentiful resource, into gasoline than it is when made from conventional crude oil.
We'll destroy the climate before we run out of fuel for our cars.