I can belive 20 minutes of cumulative time, but "added onto driving time"? Maybe for very short drives... We used to commute to one of French-named Company's research campuses at a distance of 18 miles. With a little care, that could be done in 25 mintues (~43 mph) and substantially longer in the worst parts of rush "hour". I'm having trouble imagining people willing to bike (etc) that long... but perhaps I underestimate y'all's dedication to the sport.