User blog comment:HV2308/WTTT borrowing ban - winners & losers/@comment-77.169.156.86-20170825212335

It is still possible to "borrow" cars and upgrades if you play on two devices. Just remember to not restore your cloud save until the WTT is finished. You can even collect your winnings on both devices. First collect from your primary device, perform cloud save, restore cloud save on the 2nd device and collect again. Cloud save on the 2nd device and restore cloud save on your primary device.