Recumpence

If you go to the mileage sub forum you will see many threads with descriptions on how I and Jus (the king of MPG on this forum) get our high numbers. The whole topic is hashed out at length in that forum. Oh, in 90+ degree heat with AC on, I average 53mpg in town. :) Matt

To address what Jus said earlier about the 85mph top speed being unsustainable for any distance; I agree. However, I think the benefit is when going on a long shallow downhill gradient. I was annoyed going through Wisconsin when driving down hill for extended periods with the engine running for no reason other than the 62mph programming. Frustrating. I also get annoyed that the darn engine refuses to shut off for warm-up. I realize the emission controls need to warm up and the oil needs to circulate. But, it sure seems excessive to me. Also, the AC and engine fans do run too much. From my perspective, I would bet these changes will add up to 2 mpg for most drivers. Matt

Thanks, All. Actually, we celebrated my birthday just yesterday. :) I feel appreciated. Matt

Gotcha. I am not trying to be argumentative, just trying to get everything straight in my own mind. :) Matt

Thanks for all the well wishes. :) I know people think forums are impersonal. But, I have made some good friends through various forums. Thanks again. Matt

Hmm, well, we will have to see. My last two days have been 62mpg before today. Oh, I want to tint my windows. That should help my mpg by reducing the need for ac or windows down driving. Matt

How about "Best 100 mile trip?" :) My best day yet...... Matt

That's my point, they are hot. That means the system is building up heat. Matt

Asthetics, cost, and making sure you get enough airflow even in the worst possible conditions. Fact is, the VAST majority of drivers will never come within 50% of the worst case scinerio for cooling requirements. So, blocking a part of the grilles gives easy gains. The gains are small. But, if you do enough mods, those small gains add up to a decent overall gain. Matt

Hello All, It is my 42nd birthday today. So, I am home doing paperwork and other simple stuff, but not working a full day. :) I plan to begin making a center console desk (a place to put my work clipboard in plain sight). So, Mr Max will be recieving a birthday gift today. ;) It will be TIG welded aluminum and carbon fiber........ Anyway, I hope you all have a great day too! Matt

The lower grille has about 25% of its area not doing anything. This is the area to the left and right of the opening. So my lower grille block takes that dead air that is being caught like a parachute to the left and right of the grille and diverts it around the car. Then there is the 1/3 of the opening that diverts the air around the car. So, I have roughly 50% of the air that used to be trapped in that lower grille area blocked. Basically, I have 1/2 of the air drag that used to be present with the stock grille while only having to block off 1/3 of the airflow to the lower radiator. Matt

Hey PT, I agree. I have my center grille and lower grilles covered (I actually removed my center grille and made a new one). My only caution is the lower grille hides the inverter cooler. I would HIGHLY recommend opening that up. I have about 2/3 of the original airflow opening area retained on the lower grille for cooling purposes. The max temp I have ever seen is 213 degrees. Normally it never goes above 209. With my two grilles and my smooth wheel discs I average about 2mpg improvement, total, in town and 3 to 4mpg on the expressway (depending on other factors). Matt

Hey Guys, Here is an overview of my entire trip with my observations and some cool experimantal data; First, the trip total was 900 miles. It consisted of 800 miles of interstate driving and 100 miles of through town driving. My total mileage ended at 46.7mpg for the entire trip. The last time I made this trip was totally stock and I averaged under 42mpg (38.9mpg up there and 42.2mpg coming home). So, my aero mods have increased my mpg around 4 to 5mpg on the highway and around 3mpg in town. I did some expermentation with mixed EV (under 63mph) driving and engine only running (over 65mph) and these are my findings for my car with aero mods; Above 65mph with the engine running 100% of the time, my mpg (coming home) on the expressway was averaging 44.5mpg (I had a stiff headwind coming home that was not there when we went up). However, once I dropped the speed to 63mph to allow the car to run EV occasionally, my mpg immediately shot up to over 48mpg and that was consistant over 100 miles of driving. This was through Wisconsin. It may not be consistant through flat states. However, at least with my car in hilly terrain, the EV with engine off helped my MPG tremendously. My theory on that is the engine volumetric efficiency sweetspot. That is the point of power output that achieves the highest efficiency (power per unit of gasoline versus friction and RPM). According to my Scangauge, this appears to be somewhere around 45hp. So, running the engine at 45hp results in the best efficiency. Under accelleration, that normally equates to roughly two bars on the power graph. This seems to figure correctly as most of us have found that is the accelleration sweet spot. For cruising, if the engine is running all the time, the power output was on the lower 20s (horsepower in the lower 20s) to sustain expressway speeds. However, when running under 63mph, the engine would shut off for a time, then start up. When the engine started up, it would draw around 45hp driving the car and charging the pack up. I believe this 45hp is where the engine is most efficient. So, that means the engine was running at its sweet spot whenever it was running. Then, obviously, when going downhill or on a flat with the battery relatively full, the engine would shut off and run in EV. So, the only time the engine ran was at its power output sweet spot of roughly 45hp. I hope that makes sense. :) Matt

He took a picture of the dashboard. If you divide the mile by hours on the trip you get the average MPG. This trip time reflects sitting at lights and going through towns also. So, you must take that into account. I can attest to the fact that, on smooth roads without too much wind, 70 to 75mph will net 41 to 42mpg on a stock C-Max. Matt

Yes, then the same losses exsit when accellerating. So, roughly 30% of the energy from cruising is captured and returned back into kinetic energy through regen and accellerating again. Matt

Hello All, I wanted to start this thread to give a very brief explanation of regen versus coasting. First, it is extremely important to remember that a 100% brake score does not mean you recouped 100% of the kinetic energy and converted that to battery storage. What it means is 100% of all of our slowing was achieved through regen and 0% was from the friction brakes. Second, when using regen, there are many losses convering the kinetic energy into electrical energy in the battery. There are losses through the motor/generator, losses through the inverter, losses through the transmission, tires, CV axles, wiring, and battery internal resistance. The motor/generator loss is in the range of 15% to 20% most likely. The inverter would be similar loss (maybe 10% to 15%). The transmission loss will be a minimum of 10% (probably much more). The IR of the battery and wiring adds more losses (though probably a lower % of the other losses). Third, you have all those same losses when turning that electrical energy back into kinetic energy for accelleration when the light runs green again. I have heard it said in electric car forums that only about 30% of your kinetic energy is converted to electrical energy. This seems deplorable. But consider, without regen, 100% of your energy is wasted as heat when you brake. So, a 30% return is huge compared to 0%. The take-away is this; It is generally better to coast longer and regen less if you are truly looking for the best FE possible. There are exceptions to that rule, but in general, coasting is far better than running farther up to a stop, then regenning more. Matt

No, thats not what I am saying. Even if the miles are done 100% above 63mph, the electric system still helps. When on the expressway, as you desend a hill, you will see the battery charging, Then as you climb a hill, the battery will begin discharging. This means the electric motor is aiding the car while the engine runs at high speed, therby minimizing the engine power required climbing hills and using hill desents to recover the excess energy. So, even as the engine runs non-stop at expressway speeds, the electric system is still cycling on and off thus aiding the mpg numbers on the expressway. Matt

This is a common misconception that is constantly regurgitated over and over again. However, it is not true. It is true that the engine will always run at that speed. however, it is not true that the electric system does nothing at that speed. Above 63mph, the engine runs constantly. However, the battery charges and discharges at high speeds to suplement the engine while you drive. This does add some mileage to the car. It is true that the hybrid equipment helps mlre at lower speed, but to say it does nothing at higher speed is ot true. Matt

I put 300 miles on my last tank in town when we left to go to minnessota. Well, I finished this tank on the expressway going 70mph with a full load of luggage, 3 people, and the AC blasting the entire way and still cleared 700 miles. :) Matt

I am on the road going from Chicago to Minneapolis. I am driving 70mph average with AC on averaging 49mpg! :) I love these aero mods! Oh, I may be interested in that Volt chin spoiler. PM me your info and we can talk. :) Matt

Yes, the pan should be good for 1/2 to 1mpg. :) Oh, one thing I neglected to mention is, I plan to add radiused edges to my air cutouts in those panels I added. That will increase the mpg also. Matt

Nope, not yet. So far I have done the wheel discs and the two grilles. I still need to do the upper grille, lower chin air dam, and the rear pan. I am hoping for another 2mpg with those additional mods. The guys at ecomodder say 2mpg is a conservative estimate. I also want to tint the windows. That is supposed to be good for one mpg due to less use of ac and running with windows down on hot days. Matt

Today ended at 60.9mpg. So, it looks like 60 or 61 is my new average mileage (up from 56 to 57). Matt

Here are pictures of the lower grille. As I already stated, the inverter is behind this grille as is the lower half of the engine radiator. Because the inverter is there, I purposely kept the airflow up quite high. I have 70% of the airflow of stock. The big gain in FE will not be primarily from less airflow through the radiator and inverter cooler, but from the flush mounting of the grille panel. Rather than catching air like a parachute, most of the air will be diverted around the nose of the car with only the air hitting the openings making into the radiator. Most cars recess the grilles to add visual character to the nose of the car. However, this recessing acts as a small airbrake. My grille will still allow a decent amount of airflow into the radiator without the airbrake affect. As I said about the center grille, I am not 100% sold on the look. However, it is growing on me. Oh, I may install some stainless mesh behind the grille oval openings to add some class to the look and help catch bugs and other small debris. :) Matt

I already posted this; The lower grille directs airflow over the inverter radiator (and the lower half of the radiator extends down there behind the inverter radiator). Matt