Eighteen years ago next month, my husband and I bought a new Chevy Silverado. For 14 of those years, it was our only vehicle. Our goal from day one was to make it last longer — maybe even twice as long. We still have it. As I write, it’s closing in on 250,000 miles — and still running great on its original front brakes. This truck has turned out to be really cheap transportation. And the longer…