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Old 10-27-2012, 09:52 PM   #1 (permalink)
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Wikispeed

Widispeed claims its design will do 100+ MPG at highway speed, similar around town, yet do 0-60 mph in 5 seconds:

http://www.google.com/url?sa=t&rct=j...ifWzr97KhXsyzg

Anybody believe this? After all, despite its ~1,100 lb. weight and use of Honda 1.8 liter engine, this modular design is a roadster without roof, so would have fairly stout aerodynamic drag. No idea if it has belly pan. Body shape is not quite what Hucho would prescribe. Wheels not aero optimum, etc..

So, is 100+ mpg a reasonable estimate? If not, how to make it so?


Last edited by Otto; 10-27-2012 at 10:29 PM..
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Old 10-28-2012, 03:17 PM   #2 (permalink)
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At that weight, you don't nearly need 1.8L of displacement, so the superfluous displacement is a burden in regard to FE.
It's there only to make a superfluous requirement happen : the acceleration.

It could work, with complex and expensive cylinder deactivation etc. , but it wouldn't be my choice of engine when building a 100 mpg car ...

Design claims quickly fade away on the way to production.
When a design has a target that is clearly not FE-related, I expect the mpg claim to vaporize .
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Old 10-28-2012, 04:11 PM   #3 (permalink)
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I have doubts due to the aerodynamics: Various people on this forum have gone to great lengths with boat tails, belly pans, pizza pan wheels, nose jobs, etc. and got nowhere near 114mpg on the highway at 67 mph. Granted, those folks have heavier cars than Wikispeed, but then once the vehicle is cruising on level ground at highway speed, weight is no longer that big a factor. Aero is. So, when Wikispeed claims 114mpg at 67 mph in a car with open-roof roadster drag, apparently no belly pan, not that great nose or body, etc., I have serious doubts.

I may go by there and offer to buy a gallon of fuel for a road test on I-5 to see exactly how far the car goes. Or doesn't.
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Old 10-28-2012, 08:14 PM   #4 (permalink)
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I'm a big fan of Open Source, and they have an interesting design process, but they need to work on packaging. That body on that chassis is like lipstick on a pig. It has doors thicker than a 1953 Corvette, except they aren't doors.

I haven't compared directly but the claims seem similar to the Loremo, but at least it has a hinged windshield so you don't need a cherry-picker to get you in and out of the car.
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Old 10-28-2012, 10:09 PM   #5 (permalink)
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if they are going to sell this car they gotta put in lights, doors, windows and other things that will add weight. i doubt 100 mpg combined but maybe around 80 i would believe
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Old 10-28-2012, 10:16 PM   #6 (permalink)
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I would be surprised to see even 80. Even that is a better rating than a first gen insight, without the hybrid system, lean burn, and drastically worse aero. I don't see it happening.
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Old 10-29-2012, 01:27 AM   #7 (permalink)
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Quote:
Originally Posted by 2000neon View Post
I would be surprised to see even 80. Even that is a better rating than a first gen insight, without the hybrid system, lean burn, and drastically worse aero. I don't see it happening.
I'd guesstimate about half or less of the claimed highway mileage of 114 mpg, given aero issues noted above. Even at 57 mpg, that ain't bad, but then the promoters of Wikispeed should be providing stout proof of their mileage claims if they expect to be credible if/when these things get on the road.

Also, looking at Wikispeed videos, it's apparent they lack some basic mechanical knowledge, such as proper application of gussets and washers, issues of steel vs. aluminum corrosion, and whether thin alu. L bracket supports of shocks/struts will survive many potholes. And, where's the windshield wipers on this thing, or does it just go in sunny Seattle weather every day?
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Old 10-29-2012, 06:54 PM   #8 (permalink)
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114

Quote:
Originally Posted by Otto View Post
I have doubts due to the aerodynamics: Various people on this forum have gone to great lengths with boat tails, belly pans, pizza pan wheels, nose jobs, etc. and got nowhere near 114mpg on the highway at 67 mph. Granted, those folks have heavier cars than Wikispeed, but then once the vehicle is cruising on level ground at highway speed, weight is no longer that big a factor. Aero is. So, when Wikispeed claims 114mpg at 67 mph in a car with open-roof roadster drag, apparently no belly pan, not that great nose or body, etc., I have serious doubts.

I may go by there and offer to buy a gallon of fuel for a road test on I-5 to see exactly how far the car goes. Or doesn't.
*at 1,100-lbs the EPA test weight would be 1,400-lbs
*A frontal area would be handy
*Rolling resistance data would be handy
*Do the claim 67-mph as their 114 mpg velocity?
*Do we know the road horsepower and mpg of the donor Honda at 67 mph?
If so,we could calculate the BSFC for that engine.
*If we can nail down the frontal area and tire data,knowing the BSFC at 67 mph,we should be able to reverse-engineer the road load necessary to produce 114 mpg,and from that the necessary Cd.
*The Pontiac Solstice has Cd 0.45 and is similar to the convertible Wikispeed.
*EPA 'HWY" mpg is derived at 48.2 mph average with no greater than 60 mph.We absolutely need to know if they're sticking to their 67 mph number.
*The 1991 100 mpg GM Ultralite was rated at 50 mph,close to the EPA 48.2 mph ave. velocity.She was 1,700-lb EPA test weight.
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Old 10-29-2012, 07:54 PM   #9 (permalink)
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Quote:
if they are going to sell this car they gotta put in lights, doors, windows and other things that will add weight.

To add doors they will have to completely re-engineer the chassis.
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Old 10-29-2012, 09:52 PM   #10 (permalink)
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As to the Wikispeed ~1,100 lb. empty weight, how does that compare with a dune buggy? Dune buggies are typically welded round tube structures which may or may not meet crash test criteria as claimed by Wikispeed, but then dune buggies have rollover structures but Wiki does not. Dune buggies also have proven all terrain suspensions, whereas Wikispeed does not.

So, in addition to wondering about Wiki mileage claims, I wonder if the modular structure is that great.

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