No, since the advent of EFI, wide band knock/ping sensors, and monitoring of crank position, the A/F mixture can be slightly enriched if the fuel octane used requires it.
Since about 2000 most "high" compression engines (10:1 EFI, 12:1 DFI) REQUIRE premium ONLY for full, best(?) performance.
I've been running regular here in Houston in my 2008 ES and now in my 2011 Rx since they were both new. No knocking or any noticeable difference from premium. I've tried premium and have to say I cannot tell any difference in power and it makes no difference in MPG.
I've asked at the dealership and been told premium is recommended but the sales guy who told me that said he runs regular in his cars.