Agree that the Motorhome magazine dinghy tow guides are generally your best resource. I checked 2016 and 2018 and didn't find Minis on the list. The Fiat 500s are, so that might be a possibility.
We tow a Miata, which never showed on the guides as towable, but several folks online have successfully towed their Miatas. Must be a 6 speed manual. The current one is a 2011, before that we towed a 2002. Great little cars, more smiles per mile!