60 MPG Toyota Yaris
 

I do a lot of highway with my 2014 Yaris CE and I wasn't pleased with the stock mpg.

I started with a few small things but once I made my own custom undertray, results really started to show. Now with my current setup, I have no problem maintaining 42-45mpg city and 50mpg highways. With some hypermiling, I've had my scan gauge hit 60mpg a few times now which was impossible when the car was stock.

The front grill and part of the bumper were also blocked off along with a rear diffuser (No fins just cover) and the gas tank. All I have left to cover are parts of the floors to complete the undertray.

High-speed stability has also improved dramatically along with side winds and road noise. Not the prettiest but its functional, secure, and cost me under 50$

https://ecomodder.com/forum/attachme...3&d=1647822694

https://ecomodder.com/forum/attachme...4&d=1647822704

https://ecomodder.com/forum/attachme...5&d=1647822714

Looks good, and congrats on the improved milage. Those are some very good numbers!

Good work!
What is your highway speed?

My normal highway commute consists of speeds of 55 to 70mph. Stock when going 70 I was having trouble getting EPA 37-38MPG but now I can get 42mpg at higher speeds. Not being thrown around by the wind is also very nice now.

Nice going!

Manual transmission?

Any other mods planned?

Diffuser
 

Can you show what exactly you did to your diffuser?

Yes its manual, Im sure I would have a really hard time doing this in an automatic.

I'm not sure what will be next, I got some small vortex generator fins I will put on the taillights like the prius C but that probably won't give me much gains in the real world. It's starting to get warm enough to remove my winter intake so I will be working on refining my summer one that goes into the fender.

Finishing the undertray will be next but with only about 4 feet of the center floor left to cover, the main benefits are already being felt. The car is so stable now at high speeds which is exactly what I wanted but when I do slow down, the mpg gains really show.

how do you keep the under tray in play or insert it? im looking to make one for my car too. no idea how to clip it out

🤔

Why...???

I run my exhaust heated intake year round. The hotter the air the better. Your computer will pull the fuel back to the correct air fuel ratio. Cooler air contains more oxygen thus more fuel will be needed to keep the correct ratio.

Is your mpg in Imperial or U.S. ?


>

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This is not necessarily true; current eco-cars use cool, high pressure intake air routed from in front of the radiator (Honda Insight, Toyota Prius, etc.).

After seeing these intakes at the Chicago Auto Show, I decided to try ducting my intake to the front of the car in 2020:

https://ecomodder.com/forum/member-v...723-122216.jpg

I verified that intake air temperature had been reduced by monitoring it on the Scangauge.

Statistical analysis (hypothesis testing--compares sample data to the normal distribution to determine if there is enough evidence to claim a population parameter has changed) of the fuel consumption for the 6 months previous (Jan-June) compared to the 6 months after (July-Dec) showed that consumption had been reduced, from an average 4.49 L/100 km to 4.09 L/100 km.

[QUOTE=redneck;665445]��

Why...???

I run my exhaust heated intake year round. The hotter the air the better. Your computer will pull the fuel back to the correct air fuel ratio. Cooler air contains more oxygen thus more fuel will be needed to keep the correct ratio.

Is your mpg in Imperial or U.S. ?


Yes, the Scan gauge is set to US MPG, the stock L/100km gauge I average around 4.8-5L/100KM with my mix city/highway commutes but I can get it lower.


Temperatures have risen here and I have put back my "cold air pipe" that feeds air from the fender so I get ambient temperature IATs. With the higher temperatures, there were days my car would see 60-70 degree with my winter intake and with my summer intake, they don't go over 30 which definitely improve power delivery. I'm also getting the same MPG with 30-40deg colder IATs so I don't mind switching the intakes after winter since it is not needed.

For most of the front part, I was at my local scrap yard and picked up a whole bunch of plastic screw anchors that are on every toyota fender covers. For the rear covers, there were factory holes near and on the subframe which I simply tapped some threads into and had my bolt placements. I will take more pictures when I get back under there to finish the center of the floors where I will most likely build a small metal frame to attach the last sheets. The rear section is almost completely flat now other than about 12 inches where the muffler is.


Another big plus for these covers is road noise reduction and the engine bay/body being protected from the elements. When I first got the car, a lot of small clamps and bolts in the engine compartment were showing signs of rust and that wasn't surprising since you could pretty much see the ground and all the salt would just get on everything. With the covers in place and everything rust proofed, this car should last me a very long time.

Those scoops may give you cooler IAT's but my goal with making my intake was to avoid hydro locking the engine. I made a pipe from the intake box to the inside of the drive side fender where it goes up and picks up air from behind the headlight. It gets me IAT's similar to ambient air so a scoop is really over kill and more risks of hydrolcking in the rain.

Finished up the floors today, hopefully, il be able to hit the 60mpg goal, I will report after a few fill-ups.

Update*

Driven about 1500km since the covers and I've been having a hard time crossing the 50mpg average mark, unfortunately. Sure I can hypermiling and at 70km/h cruising in 5th I get 62mpg but on average I'm having trouble crossing the 50mpg. I am happy to be able to maintain 45mpg+ without issues and at 100km/h I am at 48-49mpg. Summer is coming so hopping with the higher temperature, my average can go up.

So no improvement?

Well the only addition was the floor pans, most of the advantages seem to come from the front and rear undertray.
I would say now it's a bit more consistent at holding 48-49mpg at 100km/h compared to before.
The handling is still amazing, we had record 90km/h winds and I did a 150km highway trip, barely had any counter-steering to do. I saw another stock yaris and poor guy looked like he was drunk, wind was blowing him all over the place.

Went back under today and put a final cover over the entire thing. I put some heat reflective where the exhaust is but it really doesn't get too hot on this small engine so I'm not worried.

Also fabricated some air curtains that feed air from the fog lights.

what material did you use for the under tray?

Whatever it is has lots of fender washers.

indeed, I don't want it falling off and the front part made it through most of the winter without issues.

I used corrugated plastic for everything. The front cover is reinforced with an abs sheet and a metal frame since its where most of the impacts happen but its also the panel I remove for oil changes and service.

1500km update

The warmer temperatures are really helping and I was finally able to reach my 60mpg goal on a stretch of 10km road @ 75km/h where I do most of my testing since it's flat and can hold a constant speed. My city driving is now well into the high 40s but more importantly, on my long daily highway commutes, I can hold 54mpg at 95km/h and keep it in the 50mpg all the way up to 120km/h with some pedal feathering.

Hotter temperatures had me worried about engine temperatures but even in traffic, it never goes over 92F so I'm happy to be able to run all by covers year-round.