You can call Hertz and have them add comments in your profile. The no suv and mini-van should be easy to add and honor.

You can certainly try leather seats only, but that might be difficult for them to honor, as I don't think the interior type shows up in the computer. Also keep in mind that you need to reserve a high enough class where cars might actually have leather seats. If you are reserving class A, B, C your chances of getting leather without an upgrade are near nil and even with an upgrade is difficult at best. About the only time I get leather is when I get upgraded to a Mustang and even those might still have cloth seats. (Though all the new 2010 mustangs I have seen have leather).