While getting into the taxi I decided to light up a cigarette.
Are you sure that the smoke is not going to affect the driver. May be smart to ask.
The smoke will not affect the driver. I promise, I'm a guy.
Smoking in a cab is wrong. It will smell bad for the next rider and it can impair the driver.
It's fine. When I get home I'm going to smoke weed.
If the driver says that it is ok then it is fine, however you really should ask the driver. If they forbid it and you start smoking, you are only going to find yourself kicked out of the car.