I am losing my milage on my car. It went from 30mph to 21mph over the last year. I have taken it to a couple of mechanics to include a Toyota dealer. BTW, closest Lexus dealer is 3 hours and 2 mountain passes away. Has anyone have the same problem and have you been able to resolve it?
What did the mechanics and dealer have to say about it? Are their any stored error codes? Has all the recommended maintenance been done? Has the change in mileage gone along with a change in temperature?
The mechanics said there was nothing wrong with it. I have no idea if there are error codes but I would think they would tell me. I am super paranoid and do all the maintenance on time or before. I am a “little old lady” driver, so no fast starts or stops and no crazy driving. I can not relate it to temperature.
That’s an indication of the main drive battery not holding or delivering its charge, hence the gas engine needs to run more.
There may be regulators and other electronics responsible here too.
Get thee to the dealer.
Thank you so very much. I am calling my mechanic right now and have him check these. You are a godsend because I had no idea which way to go with this problem.
How are you measuring mileage? The most accurate way is miles driven divided by gallons of gas at a fillup.
Things that can reduce mileage:
Low tire pressure.
Sticky thermostat (I recommend change every 4-5 years).
Dragging brakes (check for a hot wheel after cruising).
Fuel leak - follow your nose.
Thick oil (make sure the right viscosity is used, likely 5W-30 or 5W-20).
If the check engine light hasn’t come on there’s likely no error codes.
Switching from pure gas to E10 should be added to your list, as should driving in colder weather in general.
I left those possibilities out because the OP said no correlation with temperature and just as likely used E10 a year ago as now.