From Wired: Commentary on the GM Volt

I was initially disappointed that the Volt was going to be a gas/electric hybrid and not an electric-only car. Given the poor performance on a charge, especially when compared to the Tesla roadster had me thinking that big companies like GM just can't get the engineers enough creative space to get the job done (GM makes money, not cars...as the old saying goes).

In actual fact, the GM Volt with its sequential hybrid is perhaps the best approach to electrifying vehicles, and surprisingly it has been around at least since the 1950's. I have been wondering why we haven't seen sequential hybrids in cars for years. The principle is the same as the Diesel-electric railroad locomotive, whereby an internal combustion engine runs an alternator that in turn provides electricity to an electric motor. In the case of the Volt, the DC electric motor gets its electricity from a Li-Ion accumulator array instead of directly from the alternator.

Even though an internal combustion engine is a great variable speed device, its optimum efficiency is in a very narrow band, usually at a low speed. On the other hand, an electric motor is more efficient at higher speeds in addition to producing maximum torque as soon as it starts turning. So it makes sense to use an internal combustion engine at a constant speed to convert energy to electricity and store it in an accumulator, where it is reconverted to work by the more efficient electric motor to drive the wheels. And this is exactly how the Volt operates.

So why not just go completely electric? The problem is always energy storage vs. efficiency. While electric motors at least 4X more energy efficient than internal combustion engines, the generation of electricity in central plants is not, as much of the electricity generated is lost in transmission in some cases over 50%. So the net efficiency of electric cars is about the same as yer good old fossil fuel banger.

So the best interim solution from an efficiency standpoint is actually what is being developed for the Volt. However I question the use of a standard 4 stroke 4 cylinder Otto cycle engine when a Stirling, Atkinson, Diesel cycle or Delatour 5 stroke would be considerably more efficient. It looks like GM is pushing hard to reuse stuff from the powertrain parts bin (especially given its failure with innovative engine designs, it probably is wise to go with what works for now).

But its a start.


The Volt Isn't A Prius. It's Better | Autopia from Wired.com

1st long trip in the Mazda6 and the CSX

We recently took both cars, my 2007 Mazda6 and my wife's 2008 Acura CSX over 1000 miles (1600 km) from our home base in Brossard, Quebec to the Outer Banks in North Carolina. We had rented a wonderful beacher in Hatteras Village for 2 weeks straddling the last week of August and the first week of September. Due to the number of people coming on the trip and with staggered family commitments requiring different arrival and departure dates, we could not get around the fact that we needed both cars.

This gave an excellent opportunity to see how well both cars performed over a long distance each with 3 passengers and luggage.

Mazda6

I had expected the Mazda to perform well. It is a very comfortable car (especially the front seats) and road noise is very well controlled. However many small cars don't handle or ride as well when fully loaded and can get downright harsh. I was also expecting less than stellar fuel economy given the full load and running the air conditioning for virtually the entire trip.

We were not disappointed. On the trip down we were 3, and my daughter had the whole back seat to herself. She had commented that the back seat was quite comfortable, but she is quite petite. On the way back, we were 4 passengers, and her 5'10" boyfriend found legroom a bit cramped, especially when compared with the CSX, but appreciated the additional hiproom. He also commented that the front seats were considerably more comfortable.

While I found this car to be stable and easy to control on the highway, it does require a deft touch with the steering. While I can drive the car smoothly, someone with less experience will tend to over-correct the very precise and responsive steering. This can render the ride on the highway quite unpleasant for passengers.

I was astonished with getting excellent fuel economy, with virtually no penalty for running the air conditioning. I averaged 7.1 liters per 100 km (31 MPG) for the entire trip, including a lot of local driving. I got a best of 6.5 l/100 km (36 MPG). The major factor in the fuel economy was actually the fuel: in areas where gasohol (10% ethanol) was mandatory, I noted a decline of nearly 1 l/100km.

Acura CSX

My son drove down and back in the CSX. His comments was the car was pleasant and easy to drive, however the tight-fitting seats did not allow for much shifting in order to relieve long-distance driving pressure. The car was very easy to control and keep steady on the highway. I attribute this to the car's longer wheelbase and its natural understeer that helps highway tracking. In this sense the CSX does not require a great degree of skill to drive. The car is somewhat firmer and tends to get harsh with passengers in the back, but this is less apparent on the highway. Much of the harshness (and lack of harshness in the Mazda) is most likely the choice of tires: the Goodyear RSAs on the Honda are probably not as compliant as the Michelin Energy MXVs on the Mazda.

My daughter's boyfriend, who drove both cars on the trip, preferred the quiet comfort of the Mazda, but mainly commented on how the cruise control compared between the Mazda's manual transmission versus the Acura's automatic. The advantage of a manual transmission is that cruise control only has the accellerator to control the speed, when an automatic will downshift to maintain speed. Also the Mazda is geared somewhat lower, and is right in the torque band at cruising speed, which means that despite the full load the engine never lugged.

As the CSX is still fairly new, we did not expect to get great mileage. Surprisingly, mileage was slightly better than the Mazda overall at 7 l/100, with a steady drop to 6.5 l/100 by the end of the trip. The Acura should be more economical with a considerably lower engine speed at cruising speeds, and it is a smaller car even though power-to-weight is virtually identical.

Finally this was the first trip using GPS, which made for a stress and hassle-free drive, especially in unfamiliar territory. We were quite impressed with both our Garmin units (look forward to another review) especially with the ability to find points of interest.