Yes, yes, yes.

Sometimes this question gets asked here on FT and sometimes people answer that it must be due to the rental agency trying to get rid of a surplus of SUVs or something, but having been on the other side of setting rates, I can corroborate what mnic and m907 said. It's a mistake. No rental rate manager would ever intentionally offload a more expensive car for less--what happens if/when they oversell on SUVs? There's no upgrade path. Far easier to oversell on cars (even if you're tight on cars but have lots of SUVs) and then have SUVs as a fallback to upgrade people into than vice versa.