What are you driving? If your car was built within the past 15 years and you've been keeping up on maintenance (replacing emission control components as they fail, as will be indicated by the check engine light), I wouldn't worry too much about the pollution aspect. Ontario's Drive Clean program has demonstrated that modern cars with functioning emission control components actually produce very little pollution.
If it's an older car, or one that isn't cleaning its exhaust as it should, then you can alleviate that guilt by either a) replacing the car, or b) replacing the failed emission control component(s).
In either case, both the bike and the car are simply modes of transportation. I would use each as the situation dictates. I know I certainly would rather relax behind the wheel of a car rather than pedal a bike after a day of rock climbing! The car is also preferred for more...intimate situations.
On the other hand, I prefer my bikes for quick and light trips, as well as for exploring new trails and routes. I hope to add commuting on nice days to that (rather short) list.