[PaleMelanesian]

Here's some different math, using my car.

The lower power consumption of the new bulbs allows more engine-off coasting before draining the battery. What are the savings of 0 fuel consumption vs idling just to power the lights?

0.25 Idle gph
$3.30 / gal fuel
$0.825 / hr Idle fuel consumption
$115 eco headlights and led tails, markers, license bulbs (ignoring brake and turn signal because their use-time is minimal)
139 hours of engine-off time required to make up the cost of the bulbs (that I wouldn't have had before).

Say I can do an extra 5 minutes of engine off per commute in winter, 1/2 the year. 10 minutes per day. 5 days a week, 26 weeks.
21 hours per year

6.6 years to pay back the bulbs.

But there's also the benefit of extended battery life.
Add in the savings you calculated above during engine-on time.
Safety is improved because I'm more willing to use my lights in marginal daylight times because of the reduced consumption.