The Prius Experiment - Fuel Economy, Hypermiling, EcoModding News and Forum

Blacktree · 03-09-2022, 01:35 PM

Hey everyone! With fuel prices skyrocketing, I decided to buy a 2nd generation Prius to save some money. Thanks to the rising price of used vehicles, I was able to sell my previous daily driver and recoup the purchase price of the Prius. So I basically got a more fuel efficient vehicle for free, thanks to some lucky timing.

I'm calling this car "The Prius Experiment" because this is new territory for me. I've never owned a hybrid vehicle before. As a matter of fact, if you told me 5 years ago that I'd become a Prius owner, I probably would have laughed. But here we are.

https://www.youtube.com/watch?v=QlqMtZTq1Cg

That said, the Prius had some issues. I got it cheap for a reason. To start, the gauge cluster and the touchscreen were both non-functional. On the 2nd generation Prius, these are common problems. The solutions are well documented in the PriusChat forum. I was able to fix the instrument cluster by replacing a bad capacitor on the circuitboard.

The touchscreen was damaged, so I bought a replacement.

https://www.youtube.com/watch?v=b_QqVbWkgtg

I also had to fix a handful of minor issues. But this is to be expected, in a 15 year old car. I was able to find most of the parts I needed, from the salvage yard.

https://www.youtube.com/watch?v=VS89BxWddQM

I also performed some basic maintenance: fluid and filter changes, new spark plugs, windshield wipers, and some light bulbs. After completing these repairs, the car was fit for use. So I put it into service. I have a ScanGauge, and the fuel economy numbers were very encouraging. However, there was one issue I couldn't ignore.

That issue was the handling, or the lack thereof. The suspension is setup for massive understeer. I found myself having to slow down for almost every turn, because the understeer was so bad. Adjusting the air pressure in the tires didn't help. Then I read about a sway bar upgrade. Apparently, the sway bars from another Toyota can be fitted to the Prius. So I did that. What a difference!

https://www.youtube.com/watch?v=KO59ib1ealc

Blacktree · 03-09-2022, 01:45 PM

OK, so we've done a bunch of work on the Prius. But so far, it's all been maintenance and repairs. What about eco-mods? I'm glad you asked. Now that the maintenance situation is under control, I can think about eco-mods. Here is a list of the mods I'm considering for the Prius. This list is tentative, so take it with a grain of salt.

-- Grille block
-- Aero wheel covers
-- Mirror delete
-- Belly pan
-- Drag spoiler

Also, there are a couple mods I may or may not do. Haven't decided yet.
-- Rear wiper delete
-- Rear wheel skirts

Also, there are some mods I do NOT plan to perform, for practical reasons.
-- Gutting the interior
-- Antenna delete
-- Boat tail

I decided to pick the low hanging fruit first. One of the easiest mods is a grille block. I bought a piece of pipe insulation from the hardware store, and stuffed it into the grille openings. I'll keep track of fuel economy, to see if it makes a difference. I'll report back after 2 or 3 fillups.

https://www.youtube.com/watch?v=KsN9QP0zR-o

That said, I think the difference for just this one mod will be very minor. The variation from one fillup to the next is probably greater. But I do plan to eventually test the difference between stock and modified (for example, grille block + wheel covers + mirror delete). That should produce more visible results.

While I'm waiting for the fuel economy data, I purchased some pizza pans. Unfortunately, they were damaged in shipping. So I had to return them. But I should still have pizza pans ready to install on the wheels soon.

freebeard · 03-09-2022, 01:52 PM

That's a lot for one day's posts, how long have you had it?

Alloys or steelies with hubcaps? How do you plan to attach the pizza pans?

Blacktree · 03-09-2022, 02:10 PM

I bought it in late October. So I've had it for about 4.5 months now. When I bought the Prius, the used car prices were just beginning to rise. When I sold the Jetta, the used car frenzy was in full swing. So I lucked out in that respect.

The car has alloys with trim rings. I was originally going to bolt the pizza pans to the trim rings. But after taking some measurements, that may not be feasible. So I'll probably bolt the pans directly to the wheels. That, of course, will require drilling holes in the wheels.

Some photos of the car:

freebeard · 03-09-2022, 02:39 PM

I ask because my friend's Prius has steelies with hub caps that look like that ...except plasticy.

If you're going to use screws, I'd be most comfortable with Helicoil inserts.

The best way is Dzus fasteners. ecomodder.com/forum/.../dzus-fastened-moon-disc-wheel-covers

Blacktree · 03-09-2022, 03:07 PM

Interesting thread. I was thinking of bolting the pans to the spokes, rather than the rim. IIRC the rim of the wheel experiences some flexing during use. But the spokes should be more dimensionally stable.

hayden55 · 03-09-2022, 03:37 PM

Does anybody make some hubcaps that go on under the lugnuts like my old honda, except for our prius? I noticed a good gain like 3-4% with carbon fiber vinyl wrapped hub caps... until i lost one one month in. lol

Piotrsko · 03-09-2022, 04:01 PM

Some camping Trailer have them. Can buy a set of two at my local campingworld

Gasoline Fumes · 03-09-2022, 04:17 PM

Quote:

Originally Posted by freebeard

I ask because my friend's Prius has steelies with hub caps that look like that ...except plasticy.

Take a closer look next time. It's an aluminum wheel with a plastic trim ring. The 3rd gen got even weirder with a full plastic cover over an aluminum wheel. I don't think any Prius came with steelies.

mpg_numbers_guy · 03-09-2022, 04:53 PM

My mom used to have a 2nd gen Prius like yours before it was totaled by a deer..

Grille block helped the car warm up faster in the winter.

Stock wheels are already light weight and optimized for aero, smooth wheel covers won't do any good, especially if they stick out any further from the wheel itself. In fact, they might actually hurt aero. Best bet is to keep the stock wheels with all 4 of the rings in tact.

If you really do want smooth wheel covers, secure them by drilling into the aero rings around the wheels, not the wheels themselves. You may notice a slight drop in mpg with adding the wheel covers due to more weight and poorer aero.

If you delete the mirrors I would definitely recommend rearward cameras if possible, but definitely add a panoramic rearview mirror.

Rear is already optimized for aero unless you add a full boattail, modifying the spoiler will likely result in a decrease in fuel economy.

Tire pressure is the single best thing you can do to help with fuel economy with the Prius, it's pretty much already near perfect in optimization for what it is.