With our 07 Prius we get 54 mpg always (I could get higher)! That’s mostly freeway/country road miles in Santa Cruz, CA area by my wife who drives 60-70 mph if possible, but not on country roads. At 400 mi/week it will pay off in about 4 years (at $3/gal). I did not buy “green” for philosophy. It’s practical.
Our Prius at 37k miles our factory Goodyear tires are getting close (the rear tires are at 3/32 or 4/32", but have been for awhile) and the fronts are better because of the batter weight in the back. My dealer recommends Yokohama Avid (86S) for P185/65 R15 (they don’t give a good reason other than that seems to make people happy). These are $105 each at the dealer, but a local tire shop has them for $60 each. Add $40 for mounting all, $25 for road hazard, and you end up with $300 for a set of 4 installed. Other tires recommended that I’ve read about are Michelin Pilot, Bridgestone Teranza, and Goodyear Integrity. You can do your own shopping.
I agree with not rotating: every 5k miles adds up. At $5/tire, that’s $20/visit. In 40K, that’s $160. I don’t rotate unless it’s included in purchase or I see signs of wear. However, your 88k for first tires seems weirdly high. You drive on ice or snow? None of my cars got that, and I’m a very frugal driver in every sense! At $100+ per tire, we’ll have saved almost two tires by not rotating when replacing (better at lower prices). I figure that’s worth the risk of not rotating.
If the Prius were a GM, Ford, etc. it would be a miracle. This is one well engineered car. But most cars are. It is just a “small” car that cost more. That said, except for Ford Focus, all domestics (and Mazda) underwhelm me each time I rent them. My prediction is that the Chevy Volt will never appear as a true competitor because of high cost and late project completion (lots of hype, no metal on the road).