The HHR's new I4 says "recommends premium but accepts regular" or something to that extent.
Is it exactly the same as putting regular in a 2.2L? With NO possibility of damage to the engine or other problems down the road from excessive knocking and pinging?
Can I trust the computer to figure out what grade I've filled the tank with and run with it?
20 cents per gallon is pretty big, especially over time. If gas prices go up again I want the option of using regular, perhaps for months at a time, is this going to be a problem if I choose the 2.4L engine?