"MPGiata" modding thread: aiming for 50 MPG with a 1990 Miata. Update: success, 55 MPG!

[MetroMPG]

MPGiata gets a new tank record: 55.6 MPG = 4.2 L/100 km. I'm callin' that 56.

New mods this tank:

- lowered suspension about 1 inch
- ... which lowered the existing air dam as well
- side skirts
- revised variable grille block, which I used more regularly than the previous version

I was a little surprised by the result considering this tank included some kayak-on-the-car trips.

--

Further thoughts on lowering:

I've scraped the air dam on a bunch of stuff, but no epic hits yet. (Though I did dodge some rather large roadkill that would have been a problem!)

Also, a portion of this weekend's road trip included a stretch of highway with pretty poor (broken) pavement, and that was fairly harsh. But not quite badenough to make me want to undo the change unless all the roads I drove on were that bad.


My friends' cottage is on an "unserviced" (to put it mildly) coarse gravel road with lots of dips, bumps & ruts. (They drive a Jeep.) I seriously considered parking at the end and walking in, but the car made it without serious incident. Video game steering technique!

[M_a_t_t]

What is "video game steering"?

[freebeard]

https://duckduckgo.com/?q=backward+drift+gta

[MetroMPG]

Think Frogger, but a Miata dodging potential air dam smashers instead of a frog dodging traffic. Left! Right! Right! Left!

[teoman]

1m^3 of space filled with helium will make your vehicle lighter by 1 kg. (Air is approx 1.25kf/m^3 and He is 0.25)

[AdrianD]

Originally Posted by MetroMPG

Since I dont use this car in the winter, I'm OK with drilling little holes underneath for mounting brackets, in this case for the skirts.

Imagine my surprise when I punctured the right side rocker panel:




It ran for a surprisingly long time! Maybe a cup or 2 of water came out.

I'm not sure how the rocker is supposed to let rainwater out (or how it gets in), but this one is obviously blocked... or used to be.

There are drain holes on each side of the jacking points on the rocker seam. Too bad everybody closes them, then the rockers rust from the inside out

[MetroMPG]

Thank you! I'll take a look. Are the drains at both the front and rear jacking points?

[AdrianD]

Yes, at both front and rear jacking points:
https://forum.miata.net/vb/showthread.php?t=587454
https://forum.miata.net/vb/showthread.php?t=311489

You should also unclog the rain rail drains (top access hole is visible in the first link)

[MetroMPG]

Thanks again! Looking outside, the car is being rained on as I type. When it dries up, I'm going to investigate.

[AJI]

Originally Posted by MetroMPG

Thanks again! Looking outside, the car is being rained on as I type. When it dries up, I'm going to investigate.

Worth poking at them with a pipe cleaner, or since you're not using it over winter, a screwdriver. Mine relieved itself all over my garage floor when I did that. Luckily it was a dry-weather car and it had just gathered a bit too much during a wash so the water was nice and clean, but a good reminder that they get a little clogged...