the 2.4l can already get over 30mpg (i get 36)
30mile electric range is laughable, in a cold winter it would be closer to 15.
You need to travel below the advertised speed limit in many states to get MGP above 30. Which is dangerous and is shown to more crashes that going at or even slightly above advertised speed.
And in the end, it is a hybrid,it will improve your city MPG more than highway. You probably, at max, can make ~23mpgs during city driving, with this system, you can bring that upto 36mpg as well, so your combine mpg will be ~36mpg.. so electric range being 30miles doesn't matter all that much. That 30 miles is not designed for you to cruise at 50mph for 30 miles ( I am not even sure the system will let you go that fast with electricity alone), it designed to saves gas when you are in traffic jam or going slow. You can spend 45 mins on a 10 mile stretch of road and with this system, you wont spend a drop of gas. When considering this 30mile range, you needs to think how much of your drive is below 35mph. So, there wont be many cases that you would need to spend all 30 mins worth of electricity in a single stretch. As it is an hybrid, it can also charge the battery to some extend during driving.
And yet my back and forward compute is ~12 miles and max speed is 30MPH, this would be a great gas saver for me.