The cited doc doesn't take into account the deep breathing that bicyclists do, leading the pollutants deeper into the lungs. So yes, there may be more in the car, but I'd argue it's doing far more damage to the cyclist. The regular coughing fits many suffer (Similar to smokers) attest to that.
I don't know any cyclists that suffer from regular coughing fits, and I ride more than 100 miles a week (and have mild asthma that I take medication for).
Even if there is an increased contact with pollutants, which is debatable, it's not certain that this causes any adverse health effects. Evidence also suggests that the health you gain from regular physical activity offsets any potential damage from breathing pollutants. Most people die of heart disease long before they get the cancer that the pollutants supposedly cause.
You will die one day even if you live in a cleanroom. Why not get some exercise before you do?
