Waiting until one product model runs out can be a costly mistake

For many consumers, there’s no sweeter sound than “free upgrade.” But in some cases, the replacement isn’t much of a step up. An energy-conscious rental-car consumer won’t care to be bumped from an economy model to a full-sized gas-guzzler. Or an airline passenger might resist moving from an aisle seat in coach to a middle seat in premium even though it has more legroom.