When Germany’s two largest parties – the CDU and the SPD – approved the coalition treaty in December 2013, it was clear that the Ministry of Transport would be led by Alexander Dobrindt. The 43-year-old who has made a career as a politician in the Bavarian CSU, the sister party of Angela Merkel’s CDU, had developed a profile on economic and education policies. Despite thus being new to the transport policy area, Mr Dobrindt managed to get quite a bit of media attention by leading his party in pushing for the introduction of a controversial motorway toll for foreign passenger cars.

This was a major concession secured by the CSU during the marathon three-month coalition talks. While the social democrats had opposed this idea and Ms Merkel publically ruled it out during the campaign, the parties agreed to go ahead with sounding out ways for a toll based on two conditions: one, any toll would have to be in conformity with European law; two, its consequences should not pose any additional burden on German car drivers.

When the proposal was first launched, not many people in Berlin or Brussels took it for more than campaign noise. The majority of the German political establishment rejected its populist undertone, and accused the CSU of scapegoating foreigners for German infrastructural woes.

The CSU is no stranger to striking populist chords – the hegemon of Bavarian politics since decades positions itself as the mouthpiece of ‘the ordinary Bavarian’. A recent case in point: its headline-making charge against the threat of low-skilled migrants from Bulgaria and Romania taking advantage of the German social welfare system, coining the infamous term Sozialtourismus, ‘social tourism’. Although not well-grounded (statistics show that unemployment among EU immigrants is below the country’s average), the call for tougher rules resonated politically across the country, even if polls show Germans generally approve of immigration of qualified workers.

Moreover, from a legal point of view, the idea was long seen as a non-starter. Any first-year European Law student could detect that this idea goes against one of the most fundamental principles of EU law, the ban of discrimination based on country of origin.

Yet rather than ringing the death knell for the foreigners-only toll idea, support came from an unlikely source. The proposal regained salience in the German discourse when the European Commission’s DG MOVE declared that a toll on the Autobahn could not prima facie be declared incompatible with EU law; only the actual content of the policy could determine its fate.

It is this hint that has kept German transport ministry officials busy over the past few weeks, struggling to come up with a legislative proposal for a toll which would satisfy the EU’s anti-discriminatory rules and avoid imposing a new burden on German car drivers.

Their latest idea: an obligatory vignette costing €100 a year. Mr Dobrindt’s ministry proposes to compensate German drivers for this fee in part by lowering the tax levied on vehicle ownership (Kfz-Steuer), in part by an ‘eco bonus’ rebate system applicable to low-emission cars, similar to the differentiation system already governing the Kfz-Steuer.

The legislative fate of this proposal is, however, all but certain.

Rather than placating concerns, Mr Dobrindt’s idea raised eyebrows at the EU level; Transport Commissioner Siim Kallas warned an ‘eco bonus’ would only be admissible if it applied to all cars, regardless of the country of registration. It is yet to be specified in the proposal, however, whether and how these rebates would be granted to foreign motorists.

Besides the European Commission (and potentially also the Court of Justice), German transport politicians will likely have to convince the powerful German automobile club ADAC of the measure’s merits – the association has doubted its economic benefits and has vocally spoken out against any toll on passenger cars. With its 18 million members it is an influential stakeholder, even though its trustworthiness was harmed this week by a revelation of its car award fixing.

In addition, a potential German toll may also soon face competition from the EU level. A working paper circulated in the transport committee of the European Parliament promotes the idea of an EU system which would allocate motorway usage permits based on the distance travelled, rather than for long time periods. The system of a toll for lorries already working successfully in Belgium, Denmark, Luxembourg, Sweden and the Netherlands could become the model for such an approach to passenger car toll collection across Europe. The idea of an EU-wide distance-based fee was picked up by the German Parliament’s transport committee chairman Martin Burkert (SPD) who called it ‘an option’.

Given the serious technical hurdles on the policy front, proposals for a toll system for passenger cars in Germany will face an uphill legislative battle. Although the bill is now confirmed to be in a ‘preparatory phase’, a fully worked-out legislative proposal for a toll on passenger cars will likely have little chance of being signed into law before early 2016.

Regardless of the toll’s fate, the on-going debate will, however, not fail to achieve its political objective: delivering precious attention and populist momentum for Mr Dobrindt’s CSU ahead of the May European Parliament elections and beyond.