I was recently gifted a 2001 Prius with 160,000 miles and have been getting around 35 MPG. From what ive read this is a bit on the low side, so im wondering if the HV battery is starting to go. Is there anything i should look at that can cause a mileage drop besides the battery? I checked the 12V battery and it puts out about 12.5V on the meter, so i think it is still in good condition. It looks like someone may have replaced it with a generic battery though. Also, did the Gen1 come with different options? I notice there are some empty spaces in the AUX panel.