GM has announced its intention to produce a plug-in Saturn VUE with a large lithium ion battery married to a 2-mode hybrid drivetrain.  This car quite possibly could be the first-ever plug-in hybrid that gets brought to the U.S. market.  I had the chance to ask the vehicle's chief engineer a few questions.

When will the plug-in VUE come to market?

We haven't announced a production date yet.

Do you have a time frame?

For the plug-in, it will go into production as early as 2010. If you look at the development path for the Volt and you look at the development path of the plug-in VUE, they are similar.

Can you tell us what the plug-in VUE's battery size will be?

We're not going to go into that level of detail right now. Its definitely going to be lithium-ion.

Is a 10-mile EV range what is expected?

That's a very reasonable expectation. When you do a plug-in what you want to do is you want to maximize the amount of range you can get from a charge-depletion mode. So when you run only on the battery, situations when you run totally on the battery, totally on electric mode, but in reality were going to have a blend of gas and electric depending on cold start up or emission or things like that. But by and large when you are running on the overall charge depleting mode, thats when you are going to generate that very high fuel economy .

Is the design for the first 10 miles will the car be capable of handling any driving requirement electric only?

Yes, but the thing you've got to remember is that it may not always be the most efficient to run only on battery under all conditions. So technically it will be capable of it, but will it in all cases? Probably not. One of the thing s we pride ourselves on is how you best integrate the vehicle. How you balance all the different environmental aspects, the emission aspects, the cost of ownership. Sometimes its not the most economical to run on battery. So we make those decisions. That why you've got all the high power controls that are in the vehicle.

So it might use gasoline even in the early miles?

Exactly. The thing we look at is charge depletion. How much fuel economy can you get during the state of the battery when you're actually using it.

So when you reach the charge depletion point and go into hybrid mode, the battery can still participate in driving the car past the EV range?

Absolutely, just like a hybrid does.

Will the battery be recharged all the way or will it operate at a lower level?

Theres a lot that we need to figure out, but the basic operation is you can charge it to the point where it can run off charge depletion again.

So it has a list of three driving operations that it can do at anytime; charge depleting, charge-sustaining, and gasoline combustion?

That's the benefit of having a larger battery. Thats why you want a lithium ion battery. You can put the energy into the battery when you have the opportunities to do so and then take advantage of them later.

Do you currently have any working prototype vehicles?

We have some very early vehicles. Mules is exactly the word that we use.

Do they have functioning packs and drivetrains?

Yes, absolutely.

Can you say which battery vendor is making the pack?

No.

Are there several different contributor companies?

We have not yet made a selection. A lot of companies are in the mix. There will only be one when we go into production.

Are there any technological hurdles that you've yet to achieve?

Of course. If you look at the difference between and two-mode VUE and a plug-in VUE whats the difference fundamentally its' the battery. Its widely understood in the industry that lithium-ion batteries represent a challenge.

So you're using nickel-metal hydride in the 2-mode?

Yes

What do expect the fuel economy to be in the 2-mode (non plug-in)?

We don't have our numbers yet. There have been a lot of reports where people reported erroneous information. What we've said is that we are projecting at least 50% improvement in combined fuel economy. The equation is 55% city, 45% highway. Right now we are confident in our ability to achieve greater than 50% combined, we're not stating the label at this point. We have to get a lot closer to our launch date before we do that.

Is it front wheel or all-wheel drive?

Front. The comparison is relative to the VUE XR front wheel drive, which is 16/23 city/hwy. The 2-mode system gives us some real opportunity because of the way we designed the system to a peak efficiency point to generate some very significant highway fuel economy.

So this car will help you align to the future CAFE standards?

Its certainly part of our strategy. All of the auto manufacturers have know change is coming we haven't known exactly what they were except that they would be significantly increased from where they are today. The hybrid alone won't get us there. Its the hybrid plus many other strategies that will allow us to meet those standards.