Toyota Auris Build Thread
 

Toyota Auris has completely the same powertrain as Prius III and same baseline specification. I will try to express all the mods and DIYs in this thread.

Current Mods:
1. CD-drive removal: -470g.
2. Number brackets removal: -300g.
3. Seat rails rear covers: -142g.
4. Lower grill block (winter only, workaround).
5. Extra towing hook removal: -570g.
6. Switch 16 OEM wheels to 15 Honda: -12.000kg.
7. Switch 205/55R16 Bridgestone to 195/65R15 Dunlop: -9.640kg.
8. Lightweight lug nuts: -0.769kg.
9. Rear speakers removal (both sides): -420g.
10. Rear headrest (middle only) + supports/locks: -374g.
11. FM antenna removal: -369g.
12. Spare tire: -14.600kg.
13. Rear middle seat-belt and lock: -815g.

TOTAL: -40.469kg.

My focus for the nearest time is weight saving.

So... I have extracted a CD drive from the headunit (yes, it is not a joke).

Weight reduction is -470g.

I haven't seen the sig in a while and forget whose it was, but "Don't look for one place to lose 100 pounds, look for 1600 places to lose an ounce."

Every bit helps!

It's a start. What sorts of things do you plan to remove? Back seats? Sound dampening? Interior trim?

Most of my driving is steady-speed, so weight removal isn't hugely beneficial for me, but if nothing else it could make the care more spritely.

I'm going to keep back seats, definitely... Some times they are still in use :)
I will try to keep balance between mpg and comfort as long as I can. I'm trying to build something that is called "sleeper" in automotive culture.

So, here are few plans for the nearest future:
1. Rear speakers.
2. Wheels.
3. Some useless interior trims.
4. Rear middle seat-belt.
5. May be some sound dampening - I'm still in doubts, as in current state it is pretty comfortable.

This is an old mod... did it 2 or 3 years ago.
Removed number plates brackets and attached number plates directly to the bumper.

At that time I was not concerned about weight reduction, so I have no information about real weight of a single bracket. But brief search on the Internet shows 150g per one bracket of the same model. So, it is 300g in total.

Yet another old mod: removed rear covers of front seats' rails.
I found that rear and front covers are different... Front covers fit fine and tight. Rear covers look terrible and actually very loose (poor design...). Also, they should protect from rear passengers, but I found that with almost no passengers and with covers there is still some stain on the back side of rails... useless.

Weight effect: -142g.

Installed 100% grill cover on the lower grill (engine). Upper grill (inverter) will be open.

Nice work. Keep us posted.

So... Wheels!

This is a research post, not a mod, because I have not yet installed anything.
Despite identical powertrain, Auris has different chassis comparing to Prius. So, I cannot blindly apply "best practices" from PriusChat - I need to do my own research.

Factory tyres are 205x55x16, Bridgestone Turanza ER300.
For some reasons, they are extremely heavy, like run-flats. There are several different variants in my size, current setup weights 9.96 kg per corner. While any other tyres including other variants of ER300 are between 8-9 kg. I have sold them already while currently driving winter tyres.

Wheels have size of 16x6.5j, ET 45mm, bolt pattern is 5x114.3mm, center bore is 60.1mm.
Factory wheel weight is 10.0 kg per corner!!! Which is extremely heavy for normal 16in wheels.

Like everyone, I want to buy a set of RPF1 :) but I will not...
In my size they weight 6.2 kg - cool, I could save 3.8 kg per corner.
1. They are expensive, especially taking into account delivery into my region (no local dealer/importer). May cost up to USD 1500 per set (wheels + delivery).
2. They are wider... still fit factory tires, but I want to gain some aero also. This is a good option for city driving, but not for interstate roads.

I did some market research and found a set of excellent used wheels!

Enkei wheels for Honda Civic Hybrid 2007 (they are Honda factory wheels).
Diameter: 15 in.
Fit width: 6j.
ET: 45 mm.
Center bore: 64.1 mm.
Bolt pattern: 5x114.3 mm.
Weight: 7.0 kg - great, especially comparing to my current setup! :eek:

They have almost completely same specification as Auris' 15in factory setup, except center bore which is easy to fix, so should fit perfectly.

They cost me USD 130 only (including delivery, wash and damages check).

Now I have to find good tyres until summer, to be continued...

Did some research about new tires...
Looking at Fulda EcoControl HP2 :rolleyes:, I will wait for Michelin e.Primacy release to see real specs, but I don't expect any magic.

So, switching from stock Bridgestone to Fulda will gain 3.6 kg per corner (14.4 kg total).
Switching to Continental will gain 2.1 kg per corner (8.3 kg total).

Great stuff. I have the previous generation Auris Hybrid which I think has similar, if not the same, running gear. (Stock image below - though mine is the same spec)

https://dam.which.co.uk/17c5c315-aee...1894217566.jpg

Aside from the Grill block I've not done anything, as it is used by my wife as well.

I'll be following this one with interest though :thumbup:

Yes, true. Prius 3Gen, Auris 1Gen, Auris 2Gen and CT200h - all have the same powertrain.

But the rest is different. (But I know that I have same rear suspension with CT200h and some front suspension parts from Auris 1Gen.)

Just found that there are 2 towing hooks in the OEM package... I will keep only 1 :rolleyes: Hope this is enough.
One hook weight is 570g.

I found some time to do wheels fitment check.

I had reasonable concerns... Honda-Enkei rim internal profile is very strange and narrow.
Honda Civic Hybrid rotors diameter is 262mm (without break caliper).
Honda Civic 4D rotors diameter is 282mm.
Toyota Auris rotors diameter is 296mm.

But it looks good after fitment, there is still some clearance.

I'm closer to the final installation :p

Summer Tyres
 

Finally!

I have bought a set of Dunlop summer tyres:
Dunlop SP Sport BluResponse 195/65R15 91H.

Real weight is 7.550 kg. (vs. estimated 7.200 kg.) per tyre.

Wheels Installation
 

And installed with Honda wheels.

So, total weight reduction (4 tyres + 4 wheels) is 21.640 kg. :thumbup:

BTW, new wheels have different lug nuts, which are smaller and MUCH lighter than Toyota OEM.
But I have not measured them in advance, so will not count it.

Lug Nuts
 

I was not able to sleep with this in mind... I did calculation for lug nuts. :rolleyes:

So, according to spec, Toyota's OEM lug nuts weight is 80g each.
But I measured, they really weight 1369g in total (68.45g each).

Honda's OEM according to spec is 30g (real weight is not yet confirmed, may be some time I will get it). All together 30g x 20 = 600g.

Weight saving is 769g.

Flat Underbody
 

I'm thinking on installing flat underbody....

Today I have measured half of the car and bought a sheet of PP to prepare mock-up.

https://ecomodder.com/forum/attachme...1&d=1619380225

Rear Speakers
 

Original rear speaker:
https://ecomodder.com/forum/attachme...1&d=1623608002

Completely removed and replaced with polyethylene cover and butyl tape:
https://ecomodder.com/forum/attachme...1&d=1623608002

Original speaker weight is 229 g. (including wiring up to the door connector and fastenings):
https://ecomodder.com/forum/attachme...1&d=1623608002
Be honest, I expected much more... but we have what we have.

Replacement weight is 20 g. only (polyethylene + butyl):
https://ecomodder.com/forum/attachme...1&d=1623608002

Note #1: I did only one side (left) for now, will replace righ side next time.

Note #2: Also, removed some insulation, but don't count it for now. I will weight all the removed insulation some time later.

Total weight reduction with this fix: 0.209 kg.

It's worth to consider not only the weight savings, but also how a narrower tyre may decrease rolling resistence.

They are rated as "B" in RR.
According to EU standards, this rating is absolute for any tyre size, not relative. So this set is pretty good from RR perspective.

Highway
 

https://ecomodder.com/forum/attachme...1&d=1624964142

Had a lot of highway driving last weekends (110-130 km/h) and FE drops significantly.
5.51 L/100 km (42.69 mpg) - does not look good.

It is time to think about some aeromodding...

Sure the rating is absolute for any tyre size, yet we can expect a smaller and lighter set to perform better regarding this perspective. A lower unsprung mass usually is pointed out as a performance advantage anyway.

Reae Speakers: Reight Side
 

Just found some time to remove the second rear speaker:

https://ecomodder.com/forum/attachme...1&d=1625327027

https://ecomodder.com/forum/attachme...1&d=1625327027

https://ecomodder.com/forum/attachme...1&d=1625327027

So, total weight of both rear speakers and rear speaker's wiring: 420 g.

Yet to do: remove front part of the wiring from the door to the headunit.

On-Board Diagnostics
 

Purchased a good OBD2 adapter and installed some useful apps to check hybrid system data.
My main area of interest is temperature (ICE, electric motors, inverter, etc.).

https://ecomodder.com/forum/attachme...1&d=1629318906

https://ecomodder.com/forum/attachme...1&d=1629318906

Preparing a PVC model, ready for fitment check:

https://ecomodder.com/forum/attachme...1&d=1632242594

Are you considering to keep PVC at some areas less prone to get it damaged by heat or would you rather make the undertray entirely of a more resistent material?

Definitely more resistent. My goal is to make a combination of alumnium + fiberglass.

PVC - is only a model to define final form, dimensions, holes, etc.

After several experiments with different materials (PP, carton, other plastics, etc.) during this summer, I found that PVC (foamed PVC) is the most suitable for making a model.

I guess you already know some rally cars are fitted with an underbody tray made out of plywood. It might seem strange at first, but maybe it's worth to take a look at.

Rally cars drive for few days :) I need something that lasts for years... In my current region climate is pretty "wet" all the year (rains, snow). I don't believe plywood will survive.

No wonder marine-grade plywood is used for that purpose on rally cars, instead of the cheapest varieties.

This is a good point, I was not thinking of that.

Maybe it's worth trying, as it surprisingly has a reasonable proportion of resistence to the weight, justifying its use even in weight-sensitive applications such as racing cars and motorcycles.

Even better is aviation plywood, which is certified to be immersed in water. Every good homebuilder puts their wing skins in the swimming pool for a week before they attach it to the wing.

As far as I understood, marine and aviation plywood are actually same material. Am I wrong?

I didn't even know there was aviation-grade plywood, yet there are even some military specifications for it.

Yup there is aviation plywood. Specs are different than marine, namely glues and assembly, no knots allowed, limited species selection........ pricey as all get out, I only know of one manufacturer, everyone went marine because it was more common and half the price and about ten times the orange box price for the junk they now sell. If you have a vintage tube and rag airplane, it's your only allowed choice for repair.

For something subjected to less stringent regulations, marine-grade plywood might be OK to address concerns regarding environmental conditions.