so..
2 light bulbs, say 55W each = 110W.
say you do 20000km per year, at an average speed of 45km/h..
say you drive during the day 70% of the time..
20000 / 45 = 444 driving hours/year
444 * 0.70 = 311 day time driving hours/year
311 * 110 = 34KWh day time lighting energy/year
1 litre of fuel ~ 16KWh of chemical energy
assume 25% efficiency for a combustion engine, and 70% for an alternator, which means
16 * 0.25 * 0.70 = 2.8KWh of energy from 1 litre of fuel
34 / 2.8 = 12 litres of fuel per year for lighting during the day!!!!!!!!!!!!!!!!
That's $18!!!!!!
And we haven't even considered the cost of changing light bulbs!!!
What about the effect on the environment!!!
shame on you!