Ultra mileage vehicle design

[Insight69]

Hello Forum!

It's been a while! I have bought another 2000 M/T Insight for modifying without limitations to achieve 200+ mpg at 55mph. What would you do to the first generation to make this happen? Serious engine mods, shaving weight and where? Body work? Deletion of equipment?

The car is strictly an R&D vehicle. I'm an individual and will be for non profit. I'd love to hear from you, and or try donated experimental parts. The car is running, but needs a front bumper and left trim at the windshield (soon to be had).

Obviously, thinking outside the box on design will be mandatory for these extremes to be reached.

Mike
(504)338-8265 (cell with unlimited texts)

[NeilBlanchard]

The Edison2 Very Light Car that weighed ~830 pounds with an ICE got about 102MPGe Combined and about 129MPGe Highway.

When they put an electric drivetrain in the VLC, it weighed ~1140 pounds, and it got about 245MPGe. The VLC has a Cd of 0.160 which is critical; but obviously the most important factor is the drivetrain efficiency. Electric drivetrain is by far the best efficiency.

I think you will want to watch this video by Oliver Kuttner several times:

http://www.youtube.com/watch?v=06wY7jGu1O0

[2000neon]

For MPG at higher speeds like 55 mph, aero mods will be a huge benefit. Since you said you have no limitations, right off the bat I will suggest a boat tail, and since you already need a front bumper, I recommend a nose cone. Also, grill block, belly pan, remove mirrors (if legal in your area), wheel spats... The sky is the limit.

Take a look at WeatherSpotter's Matrix, Basjoos' Aerocivic, and 3wheeler's Insight.

Take as much from those cars as you can. 3wheeler's thread in particular may be especially helpful since it's also an insight, and he did an incredible job with his belly pan and boattail.

[freebeard]

To double the best anyone else is doing you will need some kind of edge:


At minimum—cut the roof completely off, and add full tonneau cover with windsplit behind the driver's head.

[wmjinman]

I agree with freebeard: Cut the frontal area even more. Make narrower and lower. Maybe move rear wheels closer together if possible, or maybe even go to one rear wheel? Make into a one-seater, if it fits within your goals. I can't remember where I saw it, but someone once took a Metro & cut the top off only on the passenger's side, making the top part much narrower. I think he had a special new top gear made at a machine shop & ended up with 75 mpg.

So I'm envisioning your thing ending up looking more like a tiny Bonneville Salt Flats streamliner.

[sheepdog 44]

The only way you're going to get 200mpg or more is by severe electrification. You can get 120 mpg with complete aeromodding and hypermiling technique below the speed limit. Swapping the engine for a 600-800cc japanese microcar engine with leanburn will net you more. However the engine wont be happy with the cars weight even at 1,800lbs! You'll have a city car then unless you can shed 500 or more lbs from the car. With the Insight there isn't really much room to shed weight unless you completely stripped the car to it's frame, used plastic for all the windows and body panels. You could reconstruct the frame as a single seater and turn it into a three wheeled tadpole car running off a motorcycle engine.

The above seems rightly a time and labor intensive approach to go if you want hyperefficiency, and extremely low operating costs. What i suggest is you save all your time and money and just convert it to electricity. With the most efficient production car platform ever made as a basis for conversion, you'll get more power and much better wh/mi efficiency and range, all at a far less cost cause you'll obtain more usefullness of the smaller battery needed to accomplish it.

With a full boattail, front end, side skirts etc, you can get the CD to .17 or better. and you'll get 33% better performance or so than any production EV. Including the EV1, which never had the pleasure of running on lithium!

Or you could go halfway and just make it a plugin hybrid by leaving the engine in. Say 40 mile electric range on a 10kwh battery +-2.5kwh, and then 75mpg average on gas! What a joke the leaf and prius would look like! At that efficiency you'll be averaging far better than the cost equivalent of whatever a 200mpg car would cost to run on gas. And you could build the thing for less than half what it costs to buy a Volt or Prius plugin brand new.

You will have to beef up the suspension though for battery weight. I think the total weight of the car would be 2,000-2,400lbs depending on the components used. Thats still pretty good compared most cars.

The main reason I suggest electrification (along with aeromodding) Is because it requires less time and labor as opposed to severely altering the structural body of the insight to obtain 200mpg on gas. Also 200mpg on gas is unrealistic and comes at too high a sacrifice, unless you alter the (very poor) hybrid component of the vehicle. The only thing that comes close to 200mpg at 55mph on gas is a streamliner 125cc scooter.

[wmjinman]

Yes!! Convert to plug-in hybrid with more battery capacity - and boattail, etc. for better aero. I would actually love to have something exactly like that!!

[mort]

Originally Posted by Insight69

Hello Forum!
It's been a while! I have bought another 2000 M/T Insight for modifying without limitations to achieve 200+ mpg at 55mph.

Hi Insight69,
It seems like people are getting between 50 and 80 mpg in this car at 55 mph. I'm surprised that there isn't an Insight in the "Speed vs MPG" thread. But anyway, if you go to the ecomodder calculator. I've set up a fairly stock Insight. 1850 lb curb weight plus 150 lb driver. .008 tires is the best you can get. I just guessed at the frontal area, and slimmed the cd down below the lowest imaginable, .2 and upped the engine efficiency to .3 and it still only gets 100 mpg at 55 mph. You said thinking outside the box. Everything will need to be improved. Reduction in weight, like replacing glass with acrylic, metal body panels with plastic and lighter interior panels and seats. The frontal area could be reduced maybe a little - lower spring height and chop the roof. Could you possibly make the front axle narrower? Efficiency can be improved by replacing the engine with something that makes just enough power to to get to 55. To go 55 mph and get 200 mpg means using only 3.6 hp. So I think 200 mpg will require heroic measures.

I agree with NeilBlanchard, go electric.
I see sheepdog 44 covers this too.
-mort

[sheepdog 44]

Wow, half you hp is used to overcome aero at 40mph! I think reducing the frontal area is the top priority. Theres only so much aerodynamics will accomplish on a car. You can get the drag coefficient down to around .16cd but not much less even on a completely optimized form. There's also only so much weight you can chop out of a conventional car. At that point you hit a wall and the only thing that will help is dramatically reducing the frontal area. If you can half the frontal area, you can half the CDA, and your numbers jump big time. Half hp to overcome aero is now 60mph.

I suggest stripping of all the bodywork and glass and sit in the center of the car. Take a picture from the front and and trace a line around whatever remains, being the wheels, suspension, engine and your body. That is your ideal frontal area, now just construct the cars body skin tightly to that outline, and then follow the streamlining template for it.

Thats the best aero treatment you can possibly get, you can just forget about interior space. Whats left is up to whatever propulsion system you use. And motorcycle tires could cut your rolling resistance at the expense of handling.

[NeilBlanchard]

The stock original Insight has a Cd of 0.25 and the frontal area is 20.0 sq ft, so the CdA is 5.0 sq ft.

If you do a full aero drag treatment (bellypan, boattail, mirror delete, front wheel skirts, smooth flat wheels, grill block) and drop the Cd to 0.17, then the CdA would be 3.4 sq ft - which is a 32% improvement!

To do the same thing by deleting the roof etc., you would have to reduce the 20 sq ft frontal area down to 13.6 sq ft - which is very hard to do. The HUGE assumption is that the Cd would remain 0.25 - and I don't think it would. Doing this would completely rejigger the air flow.

What good is a car that doesn't have a roof?

The drivetrain is the single most important factor. Electric is the only drivetrain that will get a reasonably safe 2 seat car up over 200MPGe, and it will be be nearly silent and it will be *quick*. 85% plug-to-wheel beats ~35% any day.

Aerodynamics is the second most important factor. The Edison2 eVLC and Allert Jacobs streamliner are case in point - they are significantly heavier but their low drag more than compensates. EV's have a big advantage here too - virtually no drag from the cooling system because they don't need one. Aerodynamic drag is a total loss.

Weight is important, but it is much more critical for an ICE than for an EV - because of the drivetrain efficiency of an ICE sucks, really. With an EV, you only lose 10% under acceleration; rather than 75-85%. Once the car is moving, that weight helps you coast - and an EV doesn't idle. And when you need to slow down, you get to use regenerative braking, to put some of the kinetic energy back in the battery. So, weight is both bad and good.

You can do über-low rolling resistance wheels; like the Energy Return Wheel; but you would have to address the aero drag of their design.

If you don't go with an electric drivetrain, you won't be able to have a car - again the Allert Jacobs streamliner is case in point: it is a 125cc 231 pound slippery pumkin seed that carries just one person, and it gets "just" 214MPG. The Edison2 eVLC seats four tall adults and gets 245MPGe - and that could probably go over 300MPGe with an AC motor.