A question about driving...

If 70% of the nation's private car driving is due to commuting to work, what do you think the effect would be if we went from a 5 day, 8 hour per day work week to a 4 day, 10 hour per day work week? If we're cutting commuting by 20% and commuting makes up 70% of miles driven, even if we have a marginal increase of recreational driving on those days off, wouldn't we still be drastically cutting back on the total amount of driving being done?