This is an old article from last year that many have probably seen but gives some info about current partnership.
http://www.autonews.com/article/201...rtnership-to-share-technologies-confront-cost
"Toyota engineers say privately that their company has been quietly benchmarking the comparatively tiny Japanese rival, fascinated by its uncanny ability to churn out high-quality vehicles on a shoestring budget -- and to do so profitably from high-cost Japan."
http://www.autonews.com/article/20160618/OEM/306209971/toyotas-new-spirit-of-cooperation
"Cooperating with Mazda has given Toyota insights into how to manufacture in Mexico, as Toyota prepares to open its first large-scale plant there. Mazda manufactures a version of its Mazda2 sedan in Mexico for Toyota to sell in the U.S."
http://www.automotivemanufacturingsolutions.com/from-the-editor/japans-oems-continue-consolidate
"Toyota will complete its takeover of Daihatsu later this year and already effectively controls Subaru. Since 2015, it has also had a wide-ranging technical alliance with Mazda, although without any capital involvement on either side.
Full control of Subaru and Mazda by the largest Japanese car company may well transpire before too long. Ahead of such a development, Nissan has taken a 34% stake in troubled Mitsubishi by way of a fresh capital injection. This move, moreover, gives Nissan control over key decisions regarding Mitsubishis strategy and direction. Honda remains independent, as does Suzuki, but the smaller Japanese brands are gradually morphing into larger groups."