You might want to drive half-way, park on a residential street and ride the rest, for a few weeks. This would be a little easier than starting with a 25 mile commute right off. Then you get half the benefit (actually most of the benefit- the difference in health benefit between nothing and 2 hours a day is much greater than the difference between 2 hours and 4 hours).

As far as time goes, you probably spend 40 mins in the car to go 25 miles, so you already have 1.3 hours each day that you're spending in a stressful little box.