carlmungz, thank you for mentioning this. In UK you could start from ~20 airports. The idea is to fly to the start point, rent a car, and drive to the end point. We could increase the list of start airports to 100, will think of it. It is beta, and your feedback will shape the product.
Ah, right. I was using it as a UK resident trying to plan a road trip as opposed to somebody flying in and trying to plan a road trip. The 20 airports you've chosen will be enough because we only have 20 major airports with international flights.