The surge in natural gas production in the country thanks to state-of-the-art fracking techniques has led to predictions that it will one day be capable of meeting all of its own energy needs.
However, Whall and Nelson say that there is no will or intention to convert vehicle and air transportation to gas-run engines, meaning that the country will remain hindered by limited oil production.
"There has been a lot of noise around the US becoming energy independent, but while this might sound like an appealing concept, we believe these aspirations are unrealistic and likely to remain a political catchphrase rather than an economic reality," they said in a note to investors.
"There is neither government policy incentive, nor infrastructure, nor consumer appetite to transition a meaningful proportion of the US vehicle fleet to natural gas vehicles in the foreseeable future."
"One of the reasons for this is misinformation: for as long as leading energy agencies continue to talk about stellar US oil production growth, the fallacy will persist that the oil market is well supplied."
"This will hold back the move to natural gas for transportation and the need for behavioural change and greater efficiency. We can also not contemplate an alternate fuel for air transportation within our investment horizon."
The managers explain that aside from the use of natural gas for transportation fuel, the other route to US energy independence is a growth in domestic oil production to five million barrels a day.
"We believe that US tight oil [oil produced through fracking] will prove more difficult than shale gas and the early success in the Bakken and Eagle Ford formations will not be easily replicated in the non-core areas and the new plays," the managers said.
"In our view, growth of two million barrels per day from 2012 levels is more realistic, and in this scenario the US will need to import at least a quarter of its liquids requirements."
The managers say the media hype around shale gas will meet reality towards the end of this year and at that point the oil price will likely rise.
"We expect to see continued press coverage and attention directed to shale gas and tight oil this year."
"By the end of 2013, we expect the significant physical and economic challenges to tight oil production to have become better understood, and therefore the market’s confidence in a long-term higher oil price to have risen."
Investec Global Energy has made 7.75 per cent over three years, according to data from FE Analytics, while the FTSE Global Energy index has risen by 15.07 per cent.
Performance of fund vs index over 3yrs
Source: FE Analytics
The managers hold 51 per cent in the US, their joint largest overweight, and a further 10.8 per cent in Canada.
They are underweight BP and Exxon Mobil but have big positions in Valero, Suncor and Italian company ENI.
Whall and Nelson say that energy assets in the US continue to provide a strong investment case, but that many funds are giving too much attention to shale gas developments and missing the better opportunities out there.
"We are still in the midst of a profound period of change in the North American oil and gas industry and there are significant investment opportunities."
"We are particularly optimistic about the longer-term implications for US oil services and drilling companies," they added.
"We share the excitement surrounding North American oil and gas and the opportunities and challenges that this has provided for the upstream producers, midstream transporters and processors, and the downstream refiners."
"We do, however, believe that there may be too much focus within 'global' energy funds on this part of the world, when there are such strong competing investment opportunities elsewhere."
"As well as a tightening oil market, we see stronger natural gas markets globally and are particularly excited by the opportunities for LNG [liquid natural gas] and the implications that this has for pipeline gas in Europe, as LNG is sucked east."
"Demand from Asia for LNG will continue to strengthen as Japan reduces its nuclear generation capacity and China embraces natural gas as a long-term alternative to coal."
"We see a continuation of the growth in technology intensity across exploration, efficient production and development solutions, and therefore improving fortunes for the oil service companies."
"We see no end to the scramble for assets, and a shortage of exploration and development opportunities and human resources, especially within the major oil companies."
"We believe that many oil and gas companies are significantly undervalued relative to current and future commodity prices, and this is why we should continue to have active consolidation of the sector, until the equity market values these companies more appropriately."
"On this basis, we are excited about the prospects for energy in 2013 and we see opportunities to achieve sector-leading investor returns, with significant exposure to oil service and drilling companies as well as advantaged exploration and production companies."
Investec Global Energy requires a minimum investment of £1,000 and has a total expense ratio (TER) of 1.63 per cent.