Why is your vw beetle temperature light flashing red and you have low acceleration?

That depends on several reasons, first you could have a low engine coolant level, or you could have a leak in the radiator, or maybe something in the engine is not being lubricated properly and is generating more heat than usual. The only way to know for certain is to have a mechanic look at your beetle. And for your second question, cars produce lower amounts of torque when they are heated pass what they are used too. This leads to lower acceleration, or secondly, your car could be equipped with a "engine reduced power system". These systems are put on most modern cars and when the engine overheats, it automatically lowers the amount of power the engine is producing, leading to low accl.