B Stead

The BMW i3 electric car:

2799 pounds weight
101" wheelbase
61.9/62 front/rear track width
157" length
70" width
138/111 MPG equivalent


The MB B-Class Electric Drive option:

3924 pounds weight
106.3" wheelbase
61.6/61 front/rear track width
171.6" length
70.3" width
85/83 MPG equivalent


The Nissan Leaf:

3256 pounds weight
106.3" wheelbase
60.6/60.4 front/rear track width
175" length
69.7" width
126/101 MPG equivalent


The VW Golf electric option:

3391 pounds weight
103.6" estimated wheelbase
61/59.5 estimated front/rear track width
167.5" estimated length
70.5" estimated width
117/94 MPG equivalent


Now, BMW is coming close to getting these new types of cars correct but not completely.

So for the i3, they should just add more batteries and go ahead and bust the weight up to 3000 pounds. And then they should put 225 size tires on the car. And that's about it. The i3 is rear-engine and rear-wheel-drive. Then I would say that it's the batteries that are mid-ship located and so the car avoids being a flywheel not because of motor location but because of battery location.

See, all of these cars listed above have a range of less than 100 miles. Then BMW i3 simply uses its weight advantage to make a faster charging car and not a longer range car. A range-extender that busts the weight by about 265 pounds is available but if a carbon fiber car can't make an all-electric car then nothing can. So lets go all-electric and bust the weight by only 200 pounds or so and get more range as all electric
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B Stead

The bad news for electric cars is that fuel-cell cars are on the way. A fuel-cell car puts hydrogen through a fuel-cell to run the electric motor. And then the fuel-cell car has a range of about 300 miles.

But the only location with more than a dozen hydrogen fueling stations is California. They are funded for 28 hydrogen fueling stations. And then southern California is the most likely use of a fuel-cell car
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Dave68

But dang, that i3 is ugly. I guess BMW's designer was on vacation when the i3 was penned. Remember, too, that when it comes to electronics, reliability and German cars just don't go together.

B Stead

I can't help with that viewpoint.

The German cars had Bosch electronic fuel injection in the late 1960's. American cars and British cars avoided the electronic fuel injection and went through several years of poor engine operation as emission laws came into effect. Many of the British car makers went out of business.

And currently, turbocharging is highly regarded on German cars and poorly regarded on American cars. Of course the turbocharging relies on electronic engine management.

As for electric cars, well MB just uses the Tesla system. But making an electric car out of a standard car is a poor practice that results in too much vehicle weight. BMW went immediately to carbon fiber construction for their electric cars.


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Gosh, look at the BMW i8. The rear wheels are driven by an internal combustion engine while the front wheels are driven by an electric motor. This is not like a GM Volt. The i8 uses the internal combustion engine for primary drive and the electric motor as supplemental drive. The two drives together maintain high-performance while making the MPG numbers. But on top of this, the car is also carbon-fiber construction.

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Traditional cars are hopeless ? Well, look at the city MPG of the Audi R8 and then look at the city MPG of the C7 Corvette. There's something about the larger and less efficient engine that produces better fuel mileage ! So sometimes the dumb-bunnies win.

But the i8 beats both of them.

Now ignore the all-electric mode of the i8 and the city MPG is 28. And that's the correct operation of the high performance sports car.

One note, I wouldn't buy the i8 with a three-cylinder engine but would demand a four-cylinder engine.

Another note, if I were the designer of the i8 I would use the internal combustion engine as a last resort for keeping the battery charged. That's because the electric motor helps the car pull from a stop and I would keep the operation of the car consistent.

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Dave68

On the other hand, supercharging is highly regarded in American cars and not so much when it comes to German cars. It was the Germans who scoffed at hybrids from Japan and yet there are now plenty of hybrids coming from German car manufacturers. It's fairly obvious that the "not invented here" syndrome is alive and well in Europe.

B Stead

Supercharging versus turbocharging is a different subject.

But here's the thing, current supercharging tends to maintain the upper RPM range while also working in the lower ranges. Current turbocharging tends to work in the lower ranges but lose the upper RPM range. So supercharging is often chosen for sports cars while turbocharging is often chosen for sedans. The problem is that supercharging consumes a large percentage of the power that it makes and therefor at equal power outputs the supercharged engine is more highly stressed.

And then, twin turbos just means a turbo for each bank of cylinders so that the passages are short and simple. But sequential turbos means a turbo for mid-range and a turbo for high-end. On a V8 that could be four turbos ! (Variable geometry turbos are suppose to make sequential turbos unnecessary but I don't see the upper RPM range with current turbocharging.)


And hybrid cars ? They are really not necessary. Look at the Lotus Elise. It's a fast car with less than 2.0 engine size because it weighs less than 2000 pounds. So a car the size of a Camry could be built at 2500 pounds and then have a 1.8 engine for good enough sedan performance. Well, that's 30 MPG city mileage for a four-door sedan. A hybrid of equal wheelbase, track, length, and width will not have better MPG. Hybrids don't make sense when the extra cost could just go into a lighter weight construction method instead. (Except that the hybrid car could also be a lightweight car but that's two extra developments and double expensive. The BMW i8 is double expensive.)

Well, CR gets 32 MPG city out of the Camry Hybrid. The EPA is 40 MPG but that's probably a short test that begins with a perfectly charged battery. A plug-in hybrid could fix that problem such that each day begins with a perfectly charged battery. But then there's the complexity and maintenance of the hybrid system. I'm saying that a non-hybrid Camry could be built at 2500 pounds and then the premium performance engine would be 1.8 (or 2.0) instead of 3.5. The city fuel mileage could be 30 MPG instead of 21 MPG. And the 30 MPG comes close to matching the real world hybrid.

How are lightweight cars built ? Build them like the Corvette or the Evora. Those have an aluminum extrusion chassis with an SMC bodywork. The bodywork, of course, only has to be a stiff wind fairing. Or build the car out of carbon fiber. A carbon fiber car has a carbon fiber tub and then aluminum extrusions reaching to front and rear suspension
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