70 MPG US (3.3 L/100 km) challenge (non-hybrid gasoline and diesel cars)

[mpg_numbers_guy]

I've gone a few miles EOC through the WVA/VA mountains, but those aren't nearly as tall as the Rockies by far; highest elevation change is +/- 3000 ft. Probably do around 20 miles EOC on the 700 mile trips to and from university but not all at once.

[PaleMelanesian]

Over a mountain pass headed into Yellowstone a couple years ago, I found out that the Odyssey's onboard MPG gauge tops out at 150 mpg. ??? Strange design choice.

We stopped to see the view at the top, and engine-braked the whole way down. It was several miles out onto the flat land before we dropped below 150 on the gauge.

8000 ft down to 5000 or so.

[MetroMPG]

Reviving this thread with 2 nuggets:


1) My fastest speed [in the past 2 decades] and longest EOC happened simultaneously while headed to the west coast across the Rockies in my '89 Accord manual.


2) The Mirage [the Even Fancier Metro] cracked 70 MPG for a second tank this week [70.9]. Mostly because I did a lot of alternator-off trips. Now that the weather is warming up, I'm pushing for a 75 MPG tank before I park it and put the MPGiata on the road.



Did I just jinx it?

[Autobahnschleicher]

If I get my hands on a transmission from a diesel Corolla and do some aerodynamic optimisations and proper economy tires, I might get there as well.
Stock CDA was 0.527 and I'm well below that already while my engine is spinning way too high at ridiculously low load.
I'll likely record tripple digit tanks soon, just not with the Spyder...

[MetroMPG]

I assume it's possible to get away with a transmission swap in Germany because the changed ratios aren't visible to the famously strict inspection that prohibits so many other modifications?

[Autobahnschleicher]

Basicly yes, also the transmissions are identical aside from the gearing inside and the attachment mechanism for the cables.
Toyota uses C-series transmissions in all kinds of cars from the 1980s untill today.
So essentialy I'd end up swapping only a gearset, however I'd also need to do something about the odometer as it would be reading low with the taller final drive ratio.

But I'm looking around what transmission would suit me the most as I still want the car to be sporty.
Probably just swapping the 0,815 5th gear with a 0,725 or 0,682 from a different gearbox and keep the 3,941 final drive as well as gear 1-4.
That alone would drop my rpm at 100 km/h from 2900 rpm to 2400 rpm.
With a taller final drive I'd be looking at some 2000 rpm give or take.

[MetroMPG]

77.5 mpg US = 3.0 L / 100 km. [And the gauge actually reads a few % low since I'm running larger than stock diameter tires.]


[Or in other words, a bad day for you Honda Insight owners. ]

This was from a ~40 km round trip last night to go pick up a second hand floor jack.

Much pulse & glide silliness was used on the deserted and slightly rolling back roads [pulse up, glide down] that made up about 90% of the route. Alternator was also off, but that's less of a benefit in P&G than it is when just driving with load.

The outbound leg was actually over 80 MPG [tail wind].

[Piotrsko]

Really silly obvious question: why wouldn't you rig the alternator to turn on on a downhill glide? Or does it make that much of a difference?

[PaleMelanesian]

Originally Posted by Piotrsko

Really silly obvious question: why wouldn't you rig the alternator to turn on on a downhill glide? Or does it make that much of a difference?

I can answer that one: Because the engine is off for the downhill glide. With no engine running, there is nothing to run the alternator.

[Autobahnschleicher]

Realy dumb question:
Could I reduce my parasitic drag from the alternator by using a DC-DC converter and an additional battery to keep my cars battery fully charged the entire time?
Basicly using one or more powertool batteries to keep the cars battery charged and the inefficient alternator from doing anything.

I've got 12 Ah worth of 18V LiIon batteries, that should keep the battery charged up for quite a while.