I don't know if the lumen figures for car lights are low beam only but as a former driver I can tell you the motorists in the know put even more lumens on the front of their vehicles via aftermarket 'driving lights'. These are less common now that HID systems are available for standard headlights and the design of many newer cars makes mounting aftermarket light sources difficult but the object lesson here is: more is better. Just as you shouldn't drive around town on your high beams you also shouldn't blast down country lanes late at night without them! Why shouldn't cyclists have availability to multiple hundreds of lumens, even thousands to use as needed and not use when not needed just like the cagers?

H