You dont need the TCC. You can get it changed if you want but its really not worth it. What it does is it locks the torque converter to the transmission. It does this when the car is warm, in the highest gear, and over a certain speed (usually about 45mph). This helps a little with gas mileage becuase there is no power loss through torque converter slippage. When the TCC is engaged the engien will run maybe 250 - 300 rpms lower. Not a big difference. Maybe with the way gas prices are these days it would pay for itself in the next year and a half, but the car may be dead in a year and a half. Its kind of a trade off. Some will argue that the torque converter slip makes extra heat which will damage the tranny. True it does make extra heat. However, it will not damge your tranny anymore than neglecting to change the fluid every two years will. If you change the fluid at the specified intervals (a little thing called preventative maintanence), the transmission will not be affected by the TCC not engaging.