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Last weekend my town held a Smart Energy Expo, rolling it out with the fanfare of an old time circus. Naturally, I couldn't resist attending, and was glad I did. There were a number of innovative automotive products on display. One 2008 model that caught my eye was a diminutive car called the Miles ZX40S. Another petite auto was a 2007 ZENN 2.22LX.

Now, I'm no stranger to very small cars. My first sports car was a 1275-cc MG Midget, and I've driven an early Honda Civic and a 3-cylinder SAAB, as well as a number of Austin-Healeys.  All of these cars would be dwarfed by today's SUVs.

From a size point of view, the Miles ZX40S is appealing. It has over 40 cubic feet of cargo space, and can seat four. The interior actually looked reasonably spacious.

Its engine is a Chinese-made 3-phase ac induction motor that Miles claims will deliver at least 100,000 miles of service. The motor uses US-made Curtis-Albright electronics for power conversion and control. The remainder of the car is fabricated in China, but the vehicle conforms to National Highway Traffic Safety Administration standards.

The seats looked comfortable, too, and the interior was nicely trimmed and appointed. The car I saw was equipped with electric mirrors, front and rear windshield wipers, and alloy wheels. A stereo system and air conditioning are options.

The all-electric Miles ZX40S is billed as a low-speed vehicle that's NHTSA-legal at speeds up to 25 mph. Although capable of greater speeds, it’s electronically governed to not exceed the 25-mpg top speed obligation (Miles Electric Vehicles is also developing a highway-speed vehicle, slated to roll out next year).

A half dozen sealed lead-acid batteries energize the motor. Specifically, they're valve-regulated, absorbed glass matt (AGM), lead-acid types. AGMs are maintenance-free. You don't have to check cell water levels, there are no hydrogen fumes, and there's no need for equalization charging schemes. AGMs can also be stored for long periods without losing charge.

According to Miles Electric Vehicles, the ZX40S can be recharged from a 110 V outlet that can deliver 20 A or, optionally, from a 220 V 15 A source. If the battery pack hasn't been discharged beyond the maximum recommended 80% depth of discharge, time to recharge to 80% state of charge is claimed to be no more than five hours.

The total number of life cycles depends on the average depth of discharge. That is, the shorter the distance driven per cycle, the longer the batteries will last. Miles says the entire battery pack can be replaced for less than about $1500.

Mileage Numbers

Grabbing my calculator, I crunched a few numbers. If you were to drive a ZX40S under worst-case conditions, doing 45 miles before an 80% recharge, you should get 700 cycles out of a battery pack. That’s 31,500 miles of driving. At a cost of approximately 10 cents per kW-h of electricity, and with the fractional cost of the battery itself at 4.76 cents (the fractional cost to replace the entire battery pack divided by the total miles driven), the overall cost of operating the ZX40S would be 6.25 cents/mile.

YMMV

By comparison, a gasoline powered vehicle that uses petrol priced at $3.50 per gallon would cost almost 33 cents/mile to operate. Of course, your Miles ZX40S mileage may vary. The actual range you might see, and the number of battery cycles before crap-out, will likely depend on terrain traveled and the weight of the car's passengers and cargo.

Another company showing a nifty looking small electric car at the Energy Expo was ZENN Motor Company. The ZENN (zero-emissions, no-noise) comes from a Canadian-based engineering outfit piloted by Ian Clifford, a former Internet marketeer. Clifford was inspired by an old Henney Kilowatt, a 1950s electric vehicle made by the Eureka Vacuum Cleaner Co and Henney Coachbuilders.

The first ZENN was based on a Renault Dauphine. It debuted in 2001 at the Toronto International Auto Show, where it won accolades. ZENN then turned to Microcar of Europe, a maker of lightweight Diesel-powered cars, for a more robust design.

Clifford is now partnering with Richard Weir, the founder of EEStor. Weir and Clifford’s plan is to deploy state-of-the-art energy storage for the ZENN, with ultra-capacitors instead of electro-chemical batteries. One of EEStor's preliminary designs is a 52 kW-h so-called Electrical Energy Storage Unit. The EESU would charge up in mere minutes, and power a mid-size car hundreds of miles. It weighs in at 300 lb.

I felt energized walking out of the Energy Expo. As I climbed into my obsolete SAAB, with 149,000 miles on the odometer, I felt the excitement of anticipation. It's only a matter of time now before I'll probably buy a ZENN or a Miles, or something similar. My plan is to squeeze 20,000 or 30,000 more miles out of my 1994 sedan, and hope the timing will be right for a smooth transition to a reliable plug-in electric car, or perhaps a vehicle using one of the technologies I discussed in previous EN-Genius editorials (here and here). 

How about you? Comments? Questions? Write me at amm at en-genius dot net, or post your comments on our blog.