Too many rectangles, not enough gas.

1) Yes. My Gen 2 got worse MPG fast above 60 MPH. At 60 MPH it honestly rivals the Gen 3.

2) The North American Gen 2 has an internal bladder in the fuel tank, late afternoon in the summer I could get 11 gallons, winter mornings yielded 8 gallons in MS. This also affects the distance you go before the first pip disappears, Summer 160 miles, Winter 60 miles. On given tanks, the bladder may fold oddly giving varying range. My advice is to not wait until the last pip blinks.

4) A failing battery will swing rapidly between empty and full.

http://www.toyota.com/t3Portal/document/omms/MSTOYALL04_MS0011/pdf/01omsour/2004/schedmai/04w1smt.pdf

5) 5w-30 every 5,000 miles

6) Beyond the maintenance in the manual, I would recommend draining and filling the ATF WS in the transaxle routinely. Perhaps every 60,000 to 90,000 miles.

7) It is different hardware, you would need a new unit, new wiring harness, new sensors. Nothing is impossible, but I wouldn't.

 

welcome!
1) yes.
2) try letting the tank breathe for a few minutes before filling. fill slowly, holt the handle at 45 or 90 degrees.
3) no, nut there's a sticky in the gen 2 forums that might help.
4) might be a good time to start reconditioning the battery. see @jeff652 .
5) see jimbo^^^
6) follow the owners manual, take jimbo's advice, and keep your eye on the 12 volt battery.
7) no
8) get a new h/u.
9) all the best!

 

i'm the wrong person to ask, but there are some great battery threads here, where people disassemble them, use some type of model chargers to charge the individual cells i think. one good one was started by member @ryousideways .

 

1. Yes, 39 and a half overall miles per gallon is reasonable. Your miles per gallon may improve in the summer due to different gasoline mixtures
2. Since the car has a fuel bladder, the gas your car takes to fill up will vary. Nothing can be done about it as far as I know
3. There are some good guides here and on Youtube. Some common suggestions are "pulse and glide" (quickly get up to speed then have your foot just barely on the gas pedal to travel on momentum and prevent regenerative braking from kicking in), don't go much above the speed limit, brake slowly over as long a distance as is practicable, use low rolling resistance tires, and inflate tires to 42 PSI in front and 40 PSI in back (as long as that pressure is within tire limits)
4. A failing battery will drop fuel efficiency. You can tell if the battery is close to failure if the display in the Energy section shows the battery with 2 bars when you first get in your car for the day and if it quickly charges up to 7 bars then drops back down to 2 bars while driving
5. 5W30 oil is recommended, and maintenance schedule is every 5000 miles
6. Some forum members recommend draining and filling the transmission fluid every 30,000-60,000 miles
7. There's a new thread by Texas Battery Systems about that. They'll ship you the parts if you can install them
8. You can always put in an aftermarket stereo if you want, but you'd want to check compatability with steering wheel controls if you wanted to use them. I'd think adding an auxilary port to the existing one would be easier

 

5. 5W-30 oil is recommended, and maintenance schedule is every 5000 miles using dino oil. You can use a 10,000 mi OCI if you use full Synthetic oil and a genuine Toyota 90915-10003 oil filter or equivalent. The 90915-10003 filters are made in China to Toyota specs as opposed 90915-YZxxx filters made in Thailand, which I wouldn't use for a 10,000 mi interval, but ok for a 5,000 mi interval.

 

Back of a plug looks rusty (part of it that’s not cowered by socket in the picture). Maybe rain water has gotten into the spark plug tubes? How is your cowl seal?