Gas up, drivers. Oil prices that tumbled even more Friday haven’t spurred corresponding buying, prompting the International Energy Agency to slash demand forecasts for next year. A weak global economy remains to blame, the IEA says. A strong dollar works against oil demand too, as other nations lose monetary traction. The stock market dipped at the news , with the Dow down some 200 points. At least one expert predicts oil prices may hit $45 a barrel before the market evens out.