Short trips coupled with hot sunny days are hard on average MPG's

[Steve the tech geek]

I've owned my 2013 MKZ Hybrid for 3 months now and have learned that short trips & summer sun really hurt the average mileage!!!

 

Many factors add up to cause this, cold tires, cold engine, etc. But the biggest reason is:

 

The HOT INTERIOR (during the summer months) - interiors can reach 130F degrees or more when sitting in the summer sun. The AC runs at maximum capacity for about 5 minutes to extract this heat from the interior. I've done driving experiments and written a math spread sheet for calculations on this (yeah I know -- I have no life :) )

 

In my 2013 MKZ Hybrid, as an experiment, while hypermiling at 30 mph with the AC off, I achieve about 60 MPG.

Hypermiling at 30 mph with the AC at Max capacity, I see about 39 MPG!!! (Granted, this is the worst case scenario, it is much less a factor at more normal speeds and driving styles)

 

So, here's an example, on a 90 degree sunny day, you leave work and drive 2 or 3 miles to a lunch meeting. After the meeting, get back into the car, which is now again heat soaked from the summer sun, and drive back to work. Expect to get about 30 mpg on that short round trip, verses about 45 mpg if the resturaunt had been 30 miles from the office.

 

The difference being that on the short commute, tha A/C is blasting the entire commute, verses, the 30 mile commute - the majority of the trip would be running the A/C at a low level because the cabin temperarure would be normalized.

 

It's important to understand that the MKZ Hybrid's air conditioner is not less efficient at this short commute than a non hybrid car -- it's just that it is so fuel efficient, it is an unusually large ratio between the power for the A/C vs power going to the wheels for vehicle propulsion on this short trip.

 

The other extreem would be if you were drag racing your 3,500 horse power funny car for a 6 second 1/4 mile, with and without the A/C on, you're probably not going to notice that extra fuel used by the AC :) .0411 MPG Verses .0410 MPG!!!

 

So, before I put everyove into a math coma, what is the take away from all of this? -- Don't be haten' on your hybrid for not gettin' perfect mileage in the Saharah -- you're still beaten' the non hybrids!

[KenZ]

I've owned my 2013 MKZ Hybrid for 3 months now and have learned that short trips & summer sun really hurt the average mileage!!!

 

Many factors add up to cause this, cold tires, cold engine, etc. But the biggest reason is:

 

The HOT INTERIOR (during the summer months) - interiors can reach 130F degrees or more when sitting in the summer sun. The AC runs at maximum capacity for about 5 minutes to extract this heat from the interior. I've done driving experiments and written a math spread sheet for calculations on this (yeah I know -- I have no life :) )

 

In my 2013 MKZ Hybrid, as an experiment, while hypermiling at 30 mph with the AC off, I achieve about 60 MPG.

Hypermiling at 30 mph with the AC at Max capacity, I see about 39 MPG!!! (Granted, this is the worst case scenario, it is much less a factor at more normal speeds and driving styles)

 

So, here's an example, on a 90 degree sunny day, you leave work and drive 2 or 3 miles to a lunch meeting. After the meeting, get back into the car, which is now again heat soaked from the summer sun, and drive back to work. Expect to get about 30 mpg on that short round trip, verses about 45 mpg if the resturaunt had been 30 miles from the office.

 

The difference being that on the short commute, tha A/C is blasting the entire commute, verses, the 30 mile commute - the majority of the trip would be running the A/C at a low level because the cabin temperarure would be normalized.

 

It's important to understand that the MKZ Hybrid's air conditioner is not less efficient at this short commute than a non hybrid car -- it's just that it is so fuel efficient, it is an unusually large ratio between the power for the A/C vs power going to the wheels for vehicle propulsion on this short trip.

 

The other extreem would be if you were drag racing your 3,500 horse power funny car for a 6 second 1/4 mile, with and without the A/C on, you're probably not going to notice that extra fuel used by the AC :) .0411 MPG Verses .0410 MPG!!!

 

So, before I put everyove into a math coma, what is the take away from all of this? -- Don't be haten' on your hybrid for not gettin' perfect mileage in the Saharah -- you're still beaten' the non hybrids!

 

Definitely a subject close to my heart.  I had noticed the same mileage issues on short trips and the hot/humid Georgia days.  I had not taken it quite as far into the math as you did, I wish I had paid more attention in school.   I am sitting at roughly 4,000 miles after 4 months with a 43MPG lifetime average.  It has definitely been creeping up after the software update.

 

I had noticed mostly that I would get much better mileage going from home to work - than work to home.   Or from home to most anywhere - than most anywhere to home.  Difference was that the car always sits in a garage at home so it did not have that initial cool off period.  It was always in the sun at work or elsewhere.   Not sure of the effect on overall mileage but I did get into the habit of being sure the inside sunscreen was closed on the sunroof when parked outdoors.  The other thing I did which seemed to have helped with the mileage was to use remote start, so the car was cooled off by the time I got there,  In the summer, remote start turns the AC on high and turns on the AC seats automatically.  Typically it would run on battery only on remote start.  It seemed that if the battery was too depleted, it would turn on the gas engine.

 

Another interesting difference in mileage seems to be in elevation changes.  I noticed that I would almost always get 45+ MPG going from my house to the airport in Atlanta.  I would then get 35-40MPG on the return trip home.  Same roads, same speed (cruise control set to 62 before the upgrade, 75 after the upgrade), etc.  Ultimately, I figured out that there is an elevation difference of roughly 1000 feet from my home in North Georgia to the airport in Atlanta.  More downhill going to the airport and more uphill coming home.   That was the only thing I could come up with.     

 

This is my first hybrid and my first Lincoln.  So far, it has been a very good experience.

[John M Young]

Sort of off topic but I just got my 2014 MKZ Hybrid so its to new for me to comment on the new car, but I bought one of the very first Excape Hybirds. It is a  2005 ordered in June and delivered in Sept. the first production year. The Escape has all options offered at the time including AWD and no matter how I drive it the auto delivers 30 MPG summer and 29 MPG winter. In the summer the Escape may get better millage if we did not use the AC but we do. City or highway makes no difference. I know I could have changed the mileage by aggressive driving or very unaggressive driving, but I just drive whats normal for me. Car has about 130k on it now and still runs perfect and gets the same mileage as when new. The Escape has been past down to my Son to drive. 

 

The service manager at our Ford dealer told me the battery performs better when the weather is not cold. That's how he accounted for the 1MPG difference summer to winter. 

 

Since I won't change my driving habits I think I will get about 35 to 36 MPG in the MKZ. Not a lot better then the Escape since the MKZ has the second generation Hybrid system and FWD. The FWD Escapes got a couple MPG better then the AWD like I have. Don't get me wrong I really like my MKZ, and I'm sure I could do better on the MPG with very careful driving. 

Edited September 21, 2013 by John M Young

[Steve the tech geek]

KenZ

 

So, concerning your 1, 000 foot assent from the airport to home, here is the result of that calculation:

Relative to a flat commute, your commute, with its accompanying 1, 000 foot assent, the MKZ Hybrid requires an additional .14 gallons of gasoline. So, you are of course absolutely correct, it does require a consequential amount of extra fuel.

 

Another variable that we, as hybrid drivers, have to deal with when we look at mileage for a singular commute is percentage of battery charge before and after the commute. For example, if we go on a short trip starting with an almost fully charged battery, and end the trip with the battery depleted, the MPG's are going to be much higher than the other way 'round!

 

How much affect does the battery have? Well here, I can only comment on my specific car, As my battery capacity is only .45 KWH's -- no where near the advertised rating of 1.4 KWH's. (I have verified this many times with test drives and math calculations). So anyway, in my car -- .04 gallons (~5 ounces) of gas to charge the battery, so only about 1/3 the affect as your 1, 000 foot accent.

 

(By the way, for this reason, I don't believe it would be a great idea to modify our cars to plug in at night to start out with a fully charged battery in the morning -- but that is another post)

 

I hope this helps - or at least slightly interesting to somebody! :)

Edited September 23, 2013 by Steve the tech geek