Audi to showcase g-tron cars, but what is a g-tron?
Audi will have the A4 Avant and A5 Sportback g-trons on show in Frankfurt this month and, while they’re not available in the UK at the moment, we’ve had a look at what exactly g-tron means and how it works.
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G-tron models get two sets of fuel tanks – one for petrol and one for compressed natural gas (CNG). Audi has also developed its own renewable “e-gas” which is identical to CNG but is produced with wind energy.
CNG shouldn’t be confused with LPG (liquid petrol gas), which has been touted as a possible petrol and diesel alternative for decades. CNG is both cleaner and cheaper than LPG, and is easier to produce with renewable resources.
CNG – what is it?
While nowhere near as popular as other fuels, CNG is widely available in Germany. The rest of Europe is lagging behind; there are currently just four CNG filling stations in the UK. But Audi says that more consideration should be given to CNG by governments.
Audi executive Rupert Stadler commented: CNG is very clean, can be stored everywhere, you get a long range and you can refuel in two to three minutes. The strategy is right, but we need industrial partners to make it work on a wider level.”
What are the benefits?
Benefits include lower emissions and improved economy, although in reality the engine found in these two new g-tron models is based on a regular 2.0-litre TFSI unit, producing 168bhp and 270Nm of torque.
It’s a very clean fuel, with Audi stating that in CNG mode, “the g-tron models already undercut the limit values for future emission standards”. Both cars produce just 102g/km of CO2 when in CNG mode – very impressive for a 2.0-litre petrol-derived engine.
How does it work?
Aside from the extra tank, the primary difference is that the engine has been specially modified to allow the gas to ignite correctly, while an extra computer controls the pressure of the gas and allows the driver to switch between petrol and CNG.
Audi has confirmed that both its new g-trons are capable of 590 miles without a fuel stop – similar to the range offered by mainstream diesels. 311 miles can be covered with just CNG, and once the tank pressure falls, the computer will automatically switch to petrol.
Will it really take off?
Aside from the obvious lack of infrastructure, the extra tank impedes on boot space – capacity in the A4 Avant g-tron drops to 415 litres, while the A5 Sportback offers 390 – so as with any fuel, there are drawbacks.
The existing A3 g-tron hasn’t really been a hit so far even in Germany where CNG pumps abound. What’s more, as electrification and hybrid drivetrains come into their own (including numerous future Audis), it’s fair to assume CNG is unlikely to really take off here either.
For now however, if you want a non-diesel car that’s capable of big distances, the g-tron makes an excellent option. It’s more efficient than many petrol-hybrids currently available, and at the end of the day both the A4 Avant and A5 Sportback are class-leading premium cars.
You’ll just have to move to Germany…