Maximus91

From what I heard, lexus developed the engine as a new family and not the same as the 3.5 in the avalon. It might be based on it somewhat, but they said it was redically different, which is why it needed to be in its own engine family.

GS3-03

I believed the avalon engine has direct injection also, toyota don't and never advertised it, I recalled the mention of the avalon having direct injection with double vvti.
If one look at the specs, the IS has more hp and tourqe then the avalon because it is tuned differently to have more output then the avalon engine and mpg will be below the avalon somewhat with the corralation of higher hp and tourqe for the IS.
what lead me to believe the avalon has direct injection is the compression ratio, if you look at both engine, they are both 2GR engine with 11.8 to 1 compression ratio.
I could be wrong that maybe there is someway to achieve such a high compression ratio without having direct injection technology.

spwolf

I dont see reason to speculate when you simply check facts and Avalon engine does not have DI. GR engine series already used in wide array in vehicles and different configurations. However, unlike Nissan, Toyota does a bit more customization on engines, so 2.5l and 3.0 GR engines are very similar, 3.5 in avalon is simpler while 3.5l in IS350 has diffrent injection system than any of them. Also, 4.0 GR in different Toyota truck has different bore/stroke and in essence is optimized for truck use.

So IS250 will have similar engine to GS300. That means better consumption than class leading GS300 (weight, smaller displacement engine), it all gives impression that IS250 should be class leading in mpg as well.