I don't follow when you imply that the Michelins didn't wear out, but they are too soft...
Anyway Toyo are an OK brand, they have always been recognised as a budget option for Sporty drivers who will accept a higher wear rate and like an aggressive tread pattern.
Your improved economy will probably be due to having lighter tyres now (not just the width... the construction may be different) and therefore needing less energy to speed them up and slow them down. Plus the reduced rolling resistance...