80K Optional Maintenance?

I have no idea what 'optional maintenance' would be.

Can you tell us what procedures they wish to perform?

 

there really isn't much worth doing. have you changed the tranny fluid?

are your mpg's down? there can be many causes. plugs are extremely unlikely

 

Clean the throttle body?

 

i've never seen the need for it if you use top tier gas, but you may get other opinions.

your mpg's sound about right for the speed, it's hard to overcome the laws of physics.

do you have good LRR tyres? pump them up a bit?

 

Would an injector cleaning likely be of much value?

They're only going to dump some Techronine or STP into your tank. IMHO; do that yourself to save some money.

Iridium plugs can't be easily regapped - more likely to damage it by trying. They don't fall-out of specs like old style spark plugs of the past.

Transmission fluid replacement is simply a preventive maintenance measure; to prevent transmission/transaxle failure.

Hope this helps....

 

The best way to increase mpg is to slow down. It does not cost hundreds of dollars for worthless fuel treatments or unnecessary spark plugs and the extra time is insignificant versus 55-60 mph. Even the transaxle fluid is a feel good maintenance at this point.

 

Very unlikely, if it's running well, especially if you mostly use Top Tier fuel.

rjparker got it right.

Before you get to 100k, consider cleaning the EGR passages of the intake manifold, and a quick check of the EGR flow restriction number via OBD-II port.

Within reason, changing the engine oil more often than Toyota recommended is a form of "optional maintenance" many people feel adds to the life expectancy.

 

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M

Or just clean it.

 

what's the problem with the mpg? Using hypermiling skills ( in very light to no traffic ) is the best way I've found to give the computers a kind of reset. But the reset doesn't last once the traffic starts speeding up.

Not really much anyone can do to get better mpg from the Primes. Great mpg reports here can be misleading at best.
What's your lifetime mpg (if you still have it on one of your odometer or other two trip meters?

 

Yep, my wife's 2017 Prius gets way worst MPG than my 2021 Prius AWD despite me changing all all the fluid this summer (Radiator and traction battery coolant, Transmission, and brake fluid.) I clean our MAF sensors and Throttle Bodies every 25,000 miles or every 3-years, whichever comes first.)
All these jobs are pretty easy so, personally, I wouldn't pay the high costs of the dealership but would get a good local mechanic to do them BUT instruct them to only use Toyota WS Transmission oil and Toyota Super Long Life Coolant. (Even if they claim their stuff is "just as good"....nope.)

 

i wouldn't bother with the nightmare egr access on gen 4, they don't clog. obd reading would be interesting as a data point

 

I don't think there is a serviceable fuel filter. It's on the fuel pump, inside the fuel tank, in most cases.

If you have been performing the regular maintenance, anything extra likely isn't going to have a measurable impact to fuel economy.