Just did a quick search of National and you can do a Mid-size for about $73 using a free day coupon on their website (code nd35) and a contract ID. I used the American Airlines ID (5008524), but many price out the same. If you have an entertainment book, that would work too. You could use the
Walmart code open to anyone (5000304).
You also can join Emerald Club for FREE on their website and then log in to make your ressie. By being Emerald Club, you reserve an Intermediate (mid-size) and you get what is called Emerald Aisle service. You skip the counter and go straight to the garage. When you get there, you proceed to the Emerald Aisle and pick any car on that aisle. They guarantee intermediate will be there, but many times they put larger vehicles on the aisle. We have scored an Impala (full size) and a minivan on previous trips. You still only pay the intermediate price.
Take care.
Duds