Getting custom-built cars has been a part of the auto industry for many years. From improving the power curve on a small block engine through to creating custom convertibles from anything from a Hummer H3 through to a Toyota Prius, paying a company thousands of dollars for a unique vehicle happens daily across the U.S.

But over the past decade, more and more shops have begun to appear offering consumers the chance to have any car converted to electric. With prices starting from $15,000 do conversion companies offer a sensible way to get behind the wheel of an EV?

The answer depends on the outlook of the person writing the check.

Here at AllCarsElectric, we love to hear about enterprising individuals who have both the skill and time to convert their gas-guzzler to electric on little more than an old fork-lift motor and a set of second-hand batteries.

But most DIY converters are happy to tinker when things go wrong. For them, it's part of the sheer joy of converting a car to electric.

And for now, it's not the DIY conversions we're examining. It's professional conversion companies willing to convert your own car to electric or those who source cars direct from the manufacturer and then convert to electric, adding anything up to $50,000 onto the price-tag.

As Autobloggreen  recently discovered when test-driving the Amp Equinox, a professionally converted 2010 Chevy Equinox, converted vehicles have an uncanny knack of misbehaving at just the wrong point.

The company specializes in everything Porsche, going so far as to put 959 bodies onto 911 running gear

The company specializes in everything Porsche, going so far as to put 959 bodies onto 911 running gear

It isn't that professional conversions are poorly designed, or that the companies who do them are substandard. Most conversion companies have a team of highly skilled engineers who perform engineering miracles on unbelievably small resources.

But at the end of the day miracles can only take a company so far.

Developing any car costs a lot. The development of both 2011 Nissan Leaf and 2011 Chevy Volt has been well into seven figures. It's the kind of money most conversion companies simply don't have access to. Money aside, most factory-built EVs are tested for years before they make it to production and the dealer's lot.

A conversion company would have to work for many years on its drivetrain, battery and electronics to come close to a factory-built feel to any conversion.

And sadly, as the hype behind alternative fuelled vehicles increases, more and more companies are popping up, offering bespoke conversion opportunities for anything from a Smart ForTwo to an SUV.  Each company keen to take consumer's money but perhaps not always possessing the skills and engineering skills to make a truly consumer-ready car.

Add to that an often inflated price, due to hours of specialised manual labor and labor, and a converted vehicle often out-prices a competing manufactured EV.

We've driven sales demonstration units before from conversion companies where the sales demonstrator and the engineering prototype were one and the same.  Niggles with the performance, error messages and unexplained noises are explained away with the promise that "Our customer model won't have this issue."

We even once had a conversion company moan that we'd mistreated its demonstrator by accelerating too hard out of a parking lot ramp, causing the underlying lacklustre performance.

Citroen C1 ev'ie

Citroen C1 ev'ie

If experiences like this were rare it would be easy to forgive. But nearly every converted car we've seen has lacked the finish, feel and reliability of a professionally built, mainstream EV.

Just like those who fit their own body kits and do suspension drops in their back yard, DIY EV converters are willing to accept that occasionally things go wrong and need fixing.

But for those with cash but no time or skill to do things themselves, the message is clear. Unless that new car absolutely has to be fully custom and you are willing to research which of the many shops will give you a truly outstanding car in exchange for a large blank check we recommend sticking with a mainstream EV.

There are some excellent conversion companies out there, but finding them is a lengthy and expensive process.

As they say, Caveat Emptor (Buyer Beware).