I guess the better calculation would be: Cost of a typical trip w/ shades x Cost of a typical trip w/out shades Then account for the average number of trips i

I guess the better calculation would be: Cost of a typical trip w/ shades x Cost of a typical trip w/out shades Then account for the average number of trips in a year. May seem like an exaggeration but the impact of some decisions, even though seemingly tiny, may be bigger than expected.