6-8 mpg boost for a high mileage Prius

Mine has almost 200,000 miles and I yield 65 mpg per tank for the last 3 years. Are you sure I can get 71 mpg if new plugs and coils are swapped in?

 

Mine has 208k mi. and I get an average of 52 mpg. The highest I have gotten is 65 mpg. That was in the winter. Now here in Florida, running the AC constantly hurts mpgs. I can get 60 mpg if I have my fan speed on the lowest setting. @Grit how are you getting an average of 65? Any special. I've tried driving techniques and increasing my tires +2 psi. Anything else you'd suggest to get better mpgs?

 

try getting rid of excess weight

 

I did. There's nothing in the trunk.

 

spare tire? rear and passenger seat? tool kit and jack?

you have to think outside the box like @Grit

 

I could remove myself out of the car...

 

i lost 50 lbs, but i needed to

 

Do the 17in. rims help with mpgs or no? I've heard they are lighter than the steel, but they are also wider and creat more drag. I currently have the 15in. steelies.

 

it's the centrifugal force that causes larger wheels to lower the mpg's, even when lighter

 

How are you driving? If you drive 70mph+, you're mpg will drop.

Those who are getting 55mpg or more are usually doing under 60mph.
And are driving very Priusly.

 

@PriusHead05 Did this as a part of "preventive maintenance" at 120k miles and had the complete opposite effect. My mpg dropped 8-10mpg, from 52-56 down to 45-48. If you are getting good mpg (better than factory ratings) already, do not do a thing. Ride it until you have a substantial decrease and then consider changing plugs.

 

Your wheels aren't steel; the only Prius that came with steel wheels was the C.

OEM 17" are several pounds heavier than 15".

 

How many miles were in the numerator of the 35mpg, and how many now in the numerator of the 40-42?

The car's ECM computes a fairly sensitive measure called the "misfire margin", which you can read with a scan tool. This number can be negative (misfires are happening) or positive (if less than 30, at risk for misfiring; higher than 30, not really at risk, higher is better). Last time I checked mine it was something like 134. At that rate, I doubt there would be much improvement possible for me at this point. (I'm at 157,xxx, but not on the original plugs).

If your current misfire margin is lower, getting down near 30 or worse, then it is possible a change of plugs could improve something. It could also be worth investigating whether anything else is going on with the engine that could be contributing to the low margin.

Jotting down the number before and after the plug change could be another nice way of quantifying the effect of the change.

 

If your car is in good shape, just the basics including
1) Avoid short trips;
2) Avoid high speeds;
3) Avoid unnecessary braking (including regenerative);
4) Coast with engine off when safe and practical;
5) With AC, use highest thermostat setting you're willing to tolerate. The 2nd-lowest fan speed is ok.
6) Use recirculate setting with AC (whether manually or by selecting ECO mode button).

People getting significantly higher mpg than you are doing most of the above, most of the time. Unfortunately, most people don't have the patience.

 

God no, and we’ve got them. They weigh around 24 pounds apiece, and with larger OD centrifugal force is more as well. And they’re 20 mm wider.

How did the old ones look?

 

Huh? How are you thinking that relates to fuel consumption?
a = v²/r

 

The ECU is not used to the new plugs. If you want to speed up the relearning process, just disconnect the 12volt battery for a few minutes and then reconnect it.