What did you do to your Mirage today?

[Loren]

Do you ever calculate your overall mpg at the gas pump (miles driven since last tank fill/gallons pumped to refill tank)?

Finally got an opportunity to do this today! Took a little road trip over to Orlando (5-year driving instructor recertification class). Went a little something like this:

I hate driving on the interstate if I can avoid it, so I took a back roads route. The route I took was about 5 miles longer and took 40 minutes longer than the interstate route, but it's a much nicer drive. Or so I would normally think. As it turned out, the morning drive was about half good. I had to be there at 8am, so I left home at 5:30. It was a typical Sunday morning on back roads until I got about 45 minutes outside of Orlando about about 7am... then, it suddenly felt like rush hour on a weekday! And the trip home was about the same the whole way. Lots of unrelenting traffic.

In the morning, I was sort of trying to hypermile, but I was also in a hurry trying to make sure I wasn't late. Average speed for the ~2.5 hour trip was right about 50 mph. But, with parts of it being 35-45 mph roads, and parts of it being 55-60 mph road... that meant some cruising at 60 mph to make time. There was also some heavy rain at one point.

In the afternoon, I was tired, and just wanted to get home... but, not so bad that I took I-4. Took almost the same back roads route back. Traffic was awful, so it was hard to maintain a "slowish" speed, and almost impossible to do any pulse-and-glide most of the time. I did manage to drive a little slower in some places. My morning pace was 6 minutes ahead of the Google estimate, afternoon was nearly 10 minutes behind. Also some light rain.

Suffice it to say, conditions and mood were not optimal for hypermiling.

The stats were a little depressing:

Morning
122.4 miles
46.7 mpg on the display

Afternoon
108 miles
48.1 mpg on the display

That averages to 47.4 mpg from the onboard display for the day.

I filled up last night before I left, which is part of why the morning trip miles are longer. And I filled up at the same gas station when I got home. Not the same pump, though. That one was occupied. It's a fairly new gas station, though... should be consistent? Maybe?

So, 47.4 from the OBD.

Actual fuel used was 5.124 gallons.

By the trip meter:
226.5miles/5.124gals = 44.20 mpg

By Google Maps of my exact route: (should be more accurate)
230.4miles/5.124gals = 44.96

I expected the OBD display to not be 100% accurate, but it's off by more than I expected. Nearly 5% optimistic. But, it would only take a 2/10th of a gallon variance in fill-up to balance it out, so there's that possibility.

Bottom line from this trip: What I already knew. The Mirage fuel economy takes a dive at anything over 55 mph. Its sweet spot ends right about 50 mph.

[Eggman]

Nice write-up Loren.

I expected the OBD display to not be 100% accurate, but it's off by more than I expected. Nearly 5% optimistic. But, it would only take a 2/10th of a gallon variance in fill-up to balance it out, so there's that possibility.

This is consistent with my lifetime calculations. I have averaged the difference between hand-calculated MPG figures and the Mirage dashboard MID calculations, and have found that the Mirage MID computes about 2 MPG optimistic from reality. The calculations for this variance can be found in my forum Fuel Economy Log entry for Speck.

Bottom line from this trip: What I already knew. The Mirage fuel economy takes a dive at anything over 55 mph. Its sweet spot ends right about 50 mph.

That has also been my experience - above 55 mph the Mirage consumes (a lot?) more fuel per mile.

According to MetroMPG, the Mirage should be capable of 70+MPG around 25 mph. I've never seen that myself, but have never tried. Plus, I haven't been driving Speck much during nice weather.

[Mark]

Nice write-up Loren.


This is consistent with my lifetime calculations. I have averaged the difference between hand-calculated MPG figures and the Mirage dashboard MID calculations, and have found that the Mirage MID computes about 2 MPG optimistic from reality. The calculations for this variance can be found in my forum Fuel Economy Log entry for Speck.

I am not surprised mpg figures are off some, because the Mirage uses two slightly different factory tire sizes. Plus, Loren has mounted 155/60-15 tires on his Mirage. My guess is that even a slight tire difference would be seen over an entire tank of gas travel.

[Mark]

Factory tires are 22.4" or 22.6". You have 22.3" tires. I wouldn't expect an OBD mpg reading to accurate for all three tire sizes.

[Loren]

Yeah, that's one reason I expected it to be off. It was just further off than I expected.

[Loren]

According to MetroMPG, the Mirage should be capable of 70+MPG around 25 mph. I've never seen that myself, but have never tried. Plus, I haven't been driving Speck much during nice weather.

I don't doubt that. But, I'm not sure where I'll ever be able to test it! I guess the 3-4 miles of winding 2-lane road near me would work if I went out after midnight.

I find that I'm consistently disappointed in the MPG of my Mirage anytime I take a trip that requires me to drive much over 50 mph. Basically, if you're trying to "get somewhere", it falls flat.

I really enjoy and appreciate the car for driving around town.

[Dirk Diggler]

I don't doubt that. But, I'm not sure where I'll ever be able to test it! I guess the 3-4 miles of winding 2-lane road near me would work if I went out after midnight.

I find that I'm consistently disappointed in the MPG of my Mirage anytime I take a trip that requires me to drive much over 50 mph. Basically, if you're trying to "get somewhere", it falls flat.

I really enjoy and appreciate the car for driving around town.

I'm the opposite lol. I do alot of roadtrips over 5 hours going @ 75 mph. I'm usually around 3k to 3500 rpms, with cheap non-llr tires 175 65 r14s, AC on medium and Im still netting 37 to 39 mpg. Im impressed with that.

[spork]

I changed the oil myself for the first time in this car. Didn't have to jack it up or remove the plastic thing (yay), just accessed the filter from the top with a cap type filter wrench on a ratchet. Thankfully the hulk at the shop that put the drain plug on last time didn't hulk the filter too.

[precisionxt]

Changed my gear oil yesterday and put in that Redline GL-4 75W-80. To say the shifting is less jerky and smoother (especially in 1st and 2nd) is an understatement. It's like driving an entirely different car.

[Alex1a1f]

Installed a set of 2021 taillights.