Are you shifting into top gear on the highway? If so, don't. Pick the ~lowest~ gear that allows you to maintain the speed you need. In my experience, that's often second around town and third on the highway (depending on trans gearing and final drive ratio).
Paradoxically, in an EV with a series motor, you often have to shift ~up~ to accelerate! You want to keep the motor RPM high (but not overrev it of course). Driving in too high a gear keeps the motor in an inefficient speed range. It can also lead to motor overheating or even burnout. I agree with the others -- if your Optimas are from '99, they're probably near the end of their lives. You might be able to stretch the pack's life by removing the duds from the pack, and adjusting the charger (if possible) to suit the lower voltage. David Roden Akron OH USA
