The majority of F1's carmakers have now been somewhat connected to the fallout from the 'diesel-gate' scandal which last month wiped around one-third of the value of the Volkswagen Group.

With nothing like the furore that embroiled VW, Ferrari's parent company Fiat, Mercedes-Benz, Honda and Renault have nonetheless all faced some criticism for the difference between their diesel cars' reported emissions and actual emissions in real-world tests.

There has been no suggestion that these other manufacturers deliberately gamed the system – the defeat devices made famous by VW were not employed by rival carmakers.

So what's the issue?

Instead, the problem lies in the standards of the emissions tests conducted by the EU, and the difference between emissions in a test environment and in real-world driving.

According to a report in The Guardian, real-world testing of some Honda diesel models showed the cars "emitted six times the regulatory limit of NOx pollution", while at the end of September Allgemeiner Deutscher Automobil Club (ADAC) found that three of Renault's diesel models were in the top ten of polluting vehicles.

ADAC compared the cars' results from the existing EU-standard New European Driving Cycle (NDEC) tests with results obtained from more in-depth Worldwide Harmonized Light Vehicles Test Procedures (WLTC) tests expected to be adopted across the European Union in 2017.

According to ADAC, in the WLTC test Renault's Espace Energy dCi 160 emitted 11 times more NOx than it had in the NDEC test, the second-worst offender on a list of 30 tested models.

Mercedes C 220 BlueTEC was found to have double the NOx emissions under WLTC than had been found under NDEC, as did the Mercedes C 220 BlueTEC T-Modell, while the Mercedes GLA 200 d was found to be fractionally worse.

For Ferrari parent company Fiat-Chrysler, the biggest differences were found in the 4x4 ranges produced by the firm, with the Jeep Renegade 2.0 Multijet emitting 10 times more NOx in WLTC tests than found in NDEC testing, the third-worst difference on ADAC's list.

But Jeep is not the only affected FCA marque, with the Fiat 500X Multijet Start&Stop emitting seven times the NOx in WLTC tests than in the NDEC version.

The upside of VW's deliberate gaming of the emissions tests is that EU test standards have been launched onto the front pages, triggering a long-overdue discussion about the need to apply higher standards of testing given the negative environmental and health consequences of NOx emissions.

The European Union is expected to phase in real-world emissions testing in 2016, despite pushback from a number of member states whose automotive industries form a cornerstone of the national economy, and the first generation of diesels to hit the market after passing more challenging tests are anticipated in late 2017.

Formula 1 impact

What effect these changes will have on F1 remains to be seen, but given that the European automotive industry is expected to spend billions of euros ensuring that the next generation of vehicles meets more exacting test standards, it seems likely that there will be less money available for non-essential projects such as motorsport programmes.

Of particular interest given the current goings-on within the paddock is the impact the 'diesel-gate' scandal will have on Renault.

Chief Executive Carlos Ghosn is also chairman of the European Automobile Manufacturers' Association (ACEA). In the latter capacity Ghosn wrote to the EU rubbishing the possibility of any progress on diesel emissions before 2019, Reuters reported, adding that Ghosn (through ACEA) was pushing for more realistic allowable NOx emissions levels of 70 per cent higher than the current maximum.

With stricter emissions standards seemingly inevitable, and considerable work to be done – and money spent – in overhauling their current diesel range, Renault's primary focus in the short-term will be ensuring that their core business (that of making and selling cars) is able to weather the market-wide storm triggered by the VW scandal.

Renault Sport F1 is a semi-independent operation, but CEO Jerome Stoll reports directly to Ghosn – the company's sporting arm remains answerable to the larger parent group, which also decides on operating budgets.

With significant spending needed to overhaul much of their current diesel range, it is unlikely that Ghosn will sign off on the serious investment needed to bring the Renault F1 power unit into line with those produced by Ferrari and Mercedes – something that is essential if Lotus is to be competitive in 2016 and if Renault is to justify its continued (and increasing) involvement in Formula 1.