Range has been the Achilles heel of EVs ever since the first one. The problem with batteries is that they weigh a lot, take forever to charge, and aren't really efficient ways of storing energy. Everyone from the likes of the Top Gear UK crew, to Dr. Evil's alter ego, Elon Musk, to the mighty GM have tried to tackle the problem, but did a small tech startup in California called AC Propulsion invent a workable solution over 20 years ago?

If you want a car that trees will hug as you hoon down back country roads, but don't have $80k for a Tesla Model S, then your choices are limited to a Prius (bleh) or some city or subcompact car that's been tarted up as an EV (meh). With most EVs having ranges of less than 100 miles, they're only really useful as a 2nd car for families. As a primary car, or as an only car for us single people, they're essentially useless. Adding batteries to extend range adds weight, cost, and recharge time and reduces hoonability. And thanks to Telsa, there isn't exactly a glut of lithium-ion batteries on the market right now.

The serial hybrid solution - pioneered by the geniuses at Top Gear with their Hammerhead Eagle i-Thrust, and put into mass production as the successful Fisker Karma - has been around for decades in the form of diesel-electric freight trains. The on-board generator is effective for extending the range indefinitely by using readily available gasoline. However, like adding more batteries, a generator adds hoon-killing dead weight when not being used to extend range.


I considered the problem insurmountable until this morning. I was reading about cheap Coda glider chassis on eBay which got me browsing the wikis. By sheer happenstance, I stumbled upon the Wikipedia page about the AC Propusion tzero sports car. A light, mid-engined, RWD, 200 hp EV kit car is interesting all by itself, but what almost caused me to spit coffee all over my laptop screen was the picture at the bottom.


That guy is filling the tank of a trailer-mounted generator that powers the electric motor! You hook up the trailer, start the generator, and cruse down the highway. At the track you unhook and park the trailer and hoon to your heart's content with the on-board batteries. When you're done for the day, you hook the trailer back up and drive home. Of course there are more practical applications for this* like running on batteries when driving around town and using the generator trailer for the occasional road trip.

When I saw this, I slapped myself for not thinking of this first. Then I slapped myself again when I saw how long this idea has been around. AC Propulsion built the first prototype back in 1992! Yes, the magic technology that could allow you to have your EV cake and eat it, too has been around for two decades and, as far as I know, hasn't gone past the prototype stage.


Now, this isn't a one size fits all solution. For the many Americans who commute more than 100 miles round trip each day, this won't provide many benefits over a Karma-like serial hybrid. You also have the complexities of towing and backing up a trailer. To help with this, AC Propulsion developed the BackTracker trailer with computer controlled electrically steered wheels that assists the driver when backing up.

The best part of this system is that it could be retrofitted to currently existing EVs. Manufacturers could build less compromised EVs with a socket and trailer hook pre-installed in the rear. With less batteries to be installed, the base price for EVs can be reduced and customers get to decide how much car they actually need.

I honestly have no idea why this idea hasn't caught on or why it's so obscure, but I do know that it is an idea that is worth further investigation.


*As if hooning wasn't practical.

EDIT: There has been much discussion about the trailer. Here's a short Youtube video demonstrating its maneuverability.