Hauling 3000 apples past a hungry driver

A driver must move apples from town $A$ to town $B$, which lie $1000$ miles apart. He starts with $3000$ apples at $A$, but his truck holds at most $1000$ apples at once, and for every mile he drives with apples on board he eats exactly one apple. He is allowed to unload and store apples anywhere along the route and pick them up later. What is the largest number of apples he can get to $B$, and how?

About $533$ apples. While more than $2000$ apples remain he needs 3 loads, so each mile of progress costs 5 apples (3 trips forward, 2 back); after $200$ miles $2000$ are left. With 2 loads each mile costs 3, so after another $333\tfrac13$ miles $1000$ remain. The final $466\tfrac23$ miles are a single run, leaving $1000-466\tfrac23\approx533$ apples.