Upvote:2
That depends very much on the country. In New Zealand, we've never paid extra for a second driver. In the US, fees for a second driver are very common. In Germany it's been mixed but also typically cheaper than in the US. It's unlikely that a single "one size fits all" strategy would be useful. For the US, check out http://millionmilesecrets.com/2013/04/02/car-rental-additional-driver/