I had my first drive in an all-electric vehicle recently. I'm not sure, in the long run, if industry will accept this technology as an alternative to diesel-powered trucks, but plug-in trucks are certainly worth watching.

While at the NTEA Work Truck show in Indianapolis in March, members of the trade media and prospective customers were invited to test drive an assortment of alternative-power vehicles ranging from full-electric and hydraulic and electric hybrids to LNG/CNG, and propane powered trucks. There's little doubt diesel will some day be replaced as the main source of motive power for many medium- and light-duty, urban-duty-cycle trucks, like P&D bodies, curbside vans and small package delivery vans. The $64 million question is which alternate power source will prevail.

In all likelihood, each fuel -- and probably others -- will find a place in the market, depending on the application. Vehicles like this and their power systems are very application dependent.

I had a chance to drive three all-electric trucks at NTEA: a Freightliner Custom Chassis Corp. MT45-EV walk-in van (pictured above), A Smith Newton cargo van chassis (minus the cargo box), and International's E-Star curbside van.

Each was a combination of electric plug-in and electric series hybrid, meaning they had batteries that had to be plugged into a 220-volt source for their initial charge, but they also have the capability of recovering energy through regenerative braking. While decelerating, the drive wheels spin the motor/generator sending current back into the on-board batteries, thus prolonging the charge. Under the right conditions, they'll run up to 100 miles on a charge, or at least a day's driving in an urban stop 'n' go duty cycle.

At this stage of their development, there were differences in the driver displays and start-up and shut-down procedures, but everything else from the operator's perspective is remarkably similar to a traditionally powered vehicle, except the noise. There was no noise -- and that poses some problems from a pedestrian safety point of view -- but regulators are already working on that.

The vehicles were peppy to say the least. The thing with electric motors -- compared to diesel -- is they will produce 100 percent of their possible torque output at any rpm, even from a dead stop. They are very quick to accelerate, and they will hold their own up to about 30 mph. A diesel would probably overtake them at that point as horsepower begins to take over from torque, but in the city, where are you going to get much above 30 mph?

While decelerating -- with the help of the regenerative braking system -- the energy needed to charge the batteries comes from the momentum of the vehicle. The retarding power of this system is quite remarkable, and it's bound to save operators a ton of money on brake maintenance over the life of the vehicle. It's much like a compression brake, but without the noise.

The vehicles are designed so that weight distribution is similar to a typical engine-powered vehicle. The batteries are up front where the engine used to be, thus adding considerable weight to the forward part of the vehicle. The motor/generator is located around the middle of the vehicle where the transmission would be. They feel quite "natural."

A couple of manufacturers have even programmed in "creep torque" similar to what a driver would experience with an automatic transmission in drive. Just a slight bit of forward movement while in gear with the brake released. Again, totally natural in feel.

The real treat, of course, is that it's totally silent except for a faint whine from the motor. That's bound to improve a driver's state of mind at the end of a long day behind a loud diesel.

These trucks weren't designed for highway use, or even for intercity use. Primarily they will work on city routes where the mileage and on-time are predictable and within the duty-cycle parameters. At night, they are parked against the fence and plugged in for about 10 hours to gain a full charge for the next day's work. I can see these working splendidly for fleets like FedEx and UPS where loads are reasonable and driving time is minimal.

Heaters and air conditioning are all electric too, as are the rest of the vehicle systems, so care has to be taken not to tax the battery excessively, but I'm told at current evolution, the batteries can tolerate moderate electrical loads in addition to driving the vehicle.

The batteries are currently heavy and expensive -- very expensive. So much so that the technology could hardly be called commercially viable right now, but that's now. Given the right incentives to spur uptake, thus driving production scales upwards, the battery costs are bound to come down. And as battery technology improves, smaller, lighter batteries might be sufficient where large heavy ones are needed today.

Among the other advantages is reduced vehicle maintenance, particularly oil changes and brake service. One of the representatives told me there are dozens of moving parts on these vans as opposed to thousands of moving parts on a conventionally powered truck. That'll help keep costs down, and eliminating fluid changes will keep that much oil, lube and coolant out of the waste stream.

What can I really tell from a 10-minute spin around downtown Indianapolis? That downtown is where these vehicles belong. They aren't designed for high-speed driving, and over-the-road driving doesn't offer the stopping cycles needed for recharging the batteries. Dozens of these vans are already in customer hands for real-world testing and evaluation, and so far, I'm told, they are working out well.

If there's a downside, I think it's the silence. Regulators will require some kind of artificial sound source to warn pedestrians, especially the visually impaired, of the approach or proximity of these types of vehicle -- electric cars included. It could be synthesized engine sounds, or god forbid, beeps like they make now when going backwards. I hope common sense prevails here. But I can't help wondering if they'll synthesize Jake brake sounds for the deceleration cycle.

Hey, maybe there's an idea for all those Billy Big Riggers who insist on leaving the engine brake on in the city, straight pipes and all. Now that DPFs are required we won't hear the Jakes any more -- until somebody figures out how to get the synthesized Jake sounds to play through the truck's sound system so the guy inside -- and only the guy inside -- can enjoy it.