1. I'll drive you home.
2. I'll take you home by car.
Do you say #2 to mean #1?
It seems to be okay grammatically, but I'm not sure if native speakers say it....
I would only say #1. "Drive" would mean to take by car. It's a lot simpler and more natural.
I would only specify that i was taking someone by car if there was some ambiguity, or if it was not normal. If you normally took the bus or train and i was going to drive you, I might say that. But I probably would not. "I'll drive you" is just much simpler.