Rumors have been swirling for months that GM's arm in Europe, Opel, would be implicated in the dieselgate scandal-- just over the weekend serious allegations took flight that Opel does in fact use defeat devices in two diesel models.

Opel has been summoned to appear in front of a German Transport Ministry investigative committee this week to answer claims that its cars are capable of skirting emissions laws.

Der Spiegel reported last week the Opel Astra was found to contain software that will deactivate emissions control systems when the outside temperature is either below 20 degrees Celsius or above 30 degrees Celsius. Additionally it was discovered the emissions systems do not work when engine speeds exceed 2400 rpm; the car is moving faster than 145 km/h; or ambient air pressure is less than 915 millibar, indicating an elevation of more than 850 meters.

Spiegel claims the software was detected by investigating the specific motor controls, as well as observed discrepencies between the lab tests at TUV Nord in Essen and on road testing.

The 1.6-liter diesel in question was co-developed by GM and Opel, it's proliferated throughout the European lineup and is slotted for North American launch later this year in the new Cruze.

Opel is playing a game of semantics here; its official response being we do not use software "which determines whether a car is subjected to an emissions test." However the effect is ultimately the same, exhaust treatment is only operational during testing.

Meanwhile in the Netherlands, RDW, Dutch authority which issued EU type approval for the Opel Zafira Diesel, is considering a recall and a possible, but unlikely, loss of approval.

Where the situation gets muddy is when you look at EU type approvals.

Yes, the rules state "the use of defeat devices that reduce the effectiveness of emission control systems shall be prohibited," but at the same time the rules also state the prohibition shall not apply "when the need for the device is justified in terms of protecting the engine against damage or accident and for safe operation of the vehicle."

Effectively automakers can drive a bus through a loophole large as that, simply by stating an engine could be damaged while operating in certain ambient temperatures with the emissions controls operating. It's as simple as that.

Unfortunately until the the regulations are tightened up the manufacturers will continue to exploit loopholes.

Effectively the industry is operating under the old adage "if you ain't cheating, you ain't trying"-- if one automaker refuses, another won't, handing them a competitive advantage.

Call it the Lance Armstrong defense...