[jburney76@gmail.com]

I have a 2009 Prius, generation 2 that I bought a couple of months ago.

Purchase price: 4,500 US.
Mileage: 166,000 miles.
Condition: Good, with a replacement aftermarket battery, but needed several things.

What I have done:
1. Replaced spark plugs, installing stock plugs (routine)
2. Tire pressures to 35 pounds (routine).
3. Fixed leak in rear hatch area.
4. Had multifunction display repaired ($220)
5. Replaced water pump belt. (routine)
6. Cleaned VVT solenoid and filter. (not routine, but not hard)
7. Cleaned intake manifold (kinda routine)
8. Replaced air filter (routine)
9. Cleaned PCV valve (kinda routine)

MPG: With this work done, I took an 800 mile trip and got 54 mpg, driving between 60 and 75 mph. Around home I get 51 mpg. Both measurements have been confirmed at the gas pump. My local terrain is rather hilly, which explains the lower mpg.

Oil consumption: With Priuses, you can get their maintenance history at Toyota on line at toyota.com if you have the VIN. I got mine, and it was changed faithfully every 5000 miles. It consumes 1/10 of a quart every 1000 miles, a negligible amount.

Can you mod a Prius? Sure, you can mod anything. Will it work? I don't know. A few things might help. Higher tire pressure, a belly pan, deleting the radio antenna might help. Other things are a lot harder to expect any returns--lighter engine oil, wheel pizza pans, side mirror deletions, etc. but might be worth trying if legal in your area. Getting above 55 mpg on the highway is tough if you plan to drive above 65 mph, I think. Getting 55 consistently would be a great goal, though. It is worth noting, however, that anything above 55 is a matter of luck and considerable skill in operating your hybrid, and not something that comes from driving "normally".

Prius maintenance is like any hybrid: The battery is likely to need to be replaced sometime, and a new battery gives you better mileage than a refurbished one and would be my first choice probably.

What does it cost to maintain, long term? First, if you work on your own cars, they are not bad at all, but they are somewhat more expensive than a conventional car. BUT If you want someone to do your work for you, they will eat you alive:
1. It will be most efficient with low-resistance tires, so they cost an extra 100 US per tire refresh.
2. It will need a main battery perhaps every 100,000 miles, at 1600 US for refurbished, or twice that for a new battery. If you install your own, you can cut both of those numbers significantly. It will also need a 12 volt battery every 4 years for $300--a bit pricy.
3. It has has five pumps to deal with (a conventional car has 2)--a regular engine water pump, an inverter coolant pump, a coolant reserve tank pump, an air conditioning pump, and a ABS pump. The first three are easy to change and should be changed every 100,000 miles. I plan to swap junkyard parts in for the a/c pump and the entire ABS unit when needed down the line, and will keep my eyes open for having one on the shelf of each.
4. It has has no alternator, no starter, and no timing belt (it uses a timing chain), and brakes last for 100,000 miles due to regenerative braking saving your conventional brakes from much wear.
5. It is a Toyota, with Toyota engineering, which is very, very good. But it needs what every car needs--occasional work. With so much electronics, however, driving it into the ground is not a valid option, though, so you need to plan to keep it in good operating condition, with a budget of US$1000 a year or so for parts, like any used car, plus tires. If you set the funds aside, a new main battery is affordable. If you don't, the music dies when the current battery dies.