For a bit of perspective: A gallon of gas (equivalent to ~4000 cigarettes of burned organic matter) pollutes the atmosphere as much as a pack a day smoker in ~7 months.
Further, while smoker is burning a dried leaf of an ancient medicinal plant optimized over 8000 years by billions of lifelong test subjects for beneficial and pleasing properties of its smoke, the gasoline is optimized for powering engines, and not at all for inhalation of its fumes. If you put a person with dozen smokers puffing away in a closed garage, they'll all come out just fine after an hour. You put the same person with a car engine running in the same garage and he will be dead before the hour is over.