Ecomodding 2015 MX-5 Miata

[Taylor95]

New Zealand definitely has some dangerous roads. I remember one narrow road where the edge was met by a cliff- with no guardrail! Another time I was driving on a windy road at night on the south island that was probably my wordt driving experience. It was so windy that I could not go faster than 15 mph, and with each turn I felt like I was going to drive off the road. And then there were some things that were a bit annoying, like one-way bridges. Be careful out there!

What are fuel prices there like compared to where you left?

[Ecky]

Originally Posted by Taylor95

New Zealand definitely has some dangerous roads. I remember one narrow road where the edge was met by a cliff- with no guardrail! Another time I was driving on a windy road at night on the south island that was probably my wordt driving experience. It was so windy that I could not go faster than 15 mph, and with each turn I felt like I was going to drive off the road. And then there were some things that were a bit annoying, like one-way bridges. Be careful out there!

What are fuel prices there like compared to where you left?

This mirrors my experience so far. It's jaw-droppingly beautiful though. The pictures don't remotely capture it.

My last fill here was almost exactly $10USD per gallon for premium. My last fill in Minnesota was something like $5.40 for premium.

I'd wager the average vehicle here gets maybe 1.5x the fuel economy of the average in the US.

[Ecky]

Second tank is in. 75% dense city driving. With tire pressure raised to 40psi, fuel economy is up 0.6mpg from a pure highway tank. Tank was 100% top-down.

Checking out an apartment:

[ECO-AKJ]

I know the feeling on those narrow roads, I haven't been to the Netherlands but have driven on the island of St. Croix, I was driving a left-hand-drive newer Nissan Pathfinder on streets barely made for the MX-5, but they drive on the left side so that was weird for me.

One time in the Bahamas I was on a tour bus and they guide said that car crashes are rarely fatal because they drive on the left side with left-hand-drive vehicles.

[cRiPpLe_rOoStEr]

Originally Posted by ECO-AKJ

One time in the Bahamas I was on a tour bus and they guide said that car crashes are rarely fatal because they drive on the left side with left-hand-drive vehicles.

It's easier to source US-spec models due to economics of scale there, yet many Japanese-made commercial vehicles are RHD. Odd enough, in some Caribbean countries where left-hand traffic is the rule, Brazilian-made buses are available with an export-only RHD layout. But anyway, maybe it wouldn't be so bad to drive on the curbside while driving on hilly stretches...

[Ecky]

Tonight I did a bit of tire research. The car has brand new Michelin Pilot Sport 4's on it, with a very slight oversize (205mm vs 195mm, +1.7% diameter). I have not yet tried to figure out of the odometer reads high or low. This tire size actually sits right in the middle of the two MX-5 trims - some models have 17" wheels with tires another 0.8% larger.

Anyhow, I discovered a site that did comparisons of a lot of the tires I have interest in:

https://alltyretests.com/michelin-en...s-test-review/

https://alltyretests.com/michelin-pilot-sport-4/

In particular:






One thing that surprised me was how well the Vredestein Sportracs fared in their rolling resistance test. These are what I put on the front of my muscle car engine swapped Insight, and I had been surprised to find they didn't hurt fuel economy much compared with the OEM low rolling resistance tires.

Another thing, the hyper aggressive summer tires on the car really aren't that bad.

So, plugging those values into Ecomodder's calculator (and making some educated assumptions), I got the following:




Swapping the coefficient of rolling resistance value to that of Michelin Energy Savers appears to be worth approximately (and optimistically) 2mpg at highway speeds.

[Ecky]

Third tank is in! I live at the top of a ridge, around 180 meters above the city of Wellington. I'm down in the city most days, and this tank was almost 100% driving up and down, to and from the city.

Result? 6.74L/100km, or 34.9mpg. That's 17% above the car's city rating.

Halfway through the tank I increased my tire pressure from 2.75bar (40PSI) to 3bar (44PSI). There was a pretty drastic increase in harshness, and I believe tomorrow I'm going to let a bit of air back out. These are pretty large tires for such a light vehicle, and I expect I'm pretty far into diminishing returns anyway.

That aside, I ordered my first two upgrades. One replaces the long factory antenna (which I don't use) with a stubby, and the other is a clear plexiglass blockoff plate that sits between the headrests. The plate's design purpose is to drastically decrease cabin noise with the top down on the highway (which it does, supposedly) but I interpret this to also act as a spoiler and decrease drag. Since I drive with the top down 99% of the time, this ought to be a noticeable improvement.

[cRiPpLe_rOoStEr]

Originally Posted by Ecky

I drive with the top down 99% of the time

Most of the times that I still see a convertible in my hometown, even when the weather is good for top-down driving, it's up. Most likely noise is not the worse matter of concern while driving at slower speeds in city.

[COcyclist]

Subscribed. Great photos. It looks like you have chosen the perfect car for your driving conditions.

Yes to the E-bike idea. You can get one with fenders, racks and bags. The battery would make the return home up the hill easy.

[Ecky]

Currently on my wish list is a set of underbody panels. The rear diffuser was designed by a team of engineers and wind-tunnel tested to reduce drag, and the rear suspension covers need to go with it. I'd consider making the forward panels out of coroplast to save money, but considering they'd be covering the exhaust, it might not be the best idea.

Here's one set:




Here's another, without the diffuser:




Panels C and D from set #2 can be used in conjunction with set #1, though I imagine it's well into diminishing returns. More, supposedly the team that designed the black panels left some spaces open intentionally, because otherwise there can bee a lot of resonance from the exhaust and driveshaft that gets trapped in the tunnel, resulting in drone on the highway.

Euro spec cars have these two small black plastic panels that American and Japanese cars didn't get. I might drive by Mazda and see if they might be a more economical choice for the middle and front of the car, than having stamped aluminum ones shipped from Europe or the US.