Anything with a manual transmission. My 2010 Ford Fusion has a chip ignition key which means NO STEERING COLUMN LOCK, NO TRANSMISSION LOCK, and therefore no key in the ignition while towing! Woo Hoo.
The towing procedure is:
1. Put car in neutral
2. Put key in your pocket
3. Drive
For me: the aggravation and issues with automatic transmissions and requisite transmission locks are not worth it.