Main transit routes through Slovenia

Route Graz (A) - Maribor (SLO) - Zagreb (CRO)

Arriving from Austria (Graz) you arrive to border crossing Spielfeld (A) / Sentilj (SLO) and continue your way via motorway to Maribor. This is a toll road costing 0.75 EUR for cars and 1.10 EUR for cars with a trailer.
Passing Maribor you arrive to a junction and take a left turn towards Ptuj and Zagreb. From there you follow a national road through Miklavz, past Ptuj, towards border crossing Gruskovje (SLO) - Macelj (CRO) and on through Croatia.

Route Villach (A) - Jesenice - Ljubljana - Postojna - Rijeka (CRO)

Arriving from Austria (Villach) you arrive to border crossing Karavankentunnel (A) / Karavanke (SLO) and continue via motorway past Jesenice towards Radovljica. There is no motorway yet between Radovljica and Kranj so queuing traffic can be expected. The motorway continues between Kranj and Ljubljana, costing 1.60 EUR for cars and 3.50 EUR for cars with a trailer.
The motorway ends in Ljubljana at a junction, where you take a left turn and continue your way towards the center of the city. If you do not wish to see the capitol of Slovenia in more detail, you take a right turn after 2,5 km (following the signs for Koper and Trieste) onto the Ljubljana motorway ring. You exit the ring and continue your way via motorway towards Koper and Postojna. Exiting at Postojna you pay 2.10 / 3.15 EUR of toll, turn left towards Ilirska Bistrica and cross the border at Jelsane (SLO) / Rupa (CRO). From there you have a straight drive to Rijeka (CRO).

Route Villach (A) - Jesenice - Ljubljana - Koper - Pula (HR)

The route is almost the same as the one above, with the exception being, that you don't take the exit Postojna, but continue towards Koper. Before arriving there you pay 4.40 EUR / 6.70 EUR of toll. There are two routes you can take from Koper; you can drive past Koper and on towards Portoroz and border crossing Secovlje (SLO) / Plovanija (CRO), or you can take the exit Koper and drive through Smarje towards border crossing Dragonja (SLO) / Kastel (CRO). Both routes will take you to the new Istrian motorway towards Pula (CRO).

Route Villach (A) - Ljubljana - Zagreb (CRO)

Arriving from Austria (Villach) you arrive to border crossing Karavankentunnel (A) / Karavanke (SLO) and continue via motorway past Jesenice towards Radovljica. There is no motorway yet between Radovljica and Kranj so queuing traffic can be expected. The motorway continues between Kranj and Ljubljana, costing 1.60 EUR for cars and 2.35 EUR for cars with a trailer.
The motorway ends in Ljubljana at a junction, where you take a left turn and continue your way towards the center of the city. If you do not wish to see the capitol of Slovenia in more detail, you take a right turn after 2,5 km (following the signs for Novo mesto / Zagreb) onto the Ljubljana motorway ring.
You follow the ring and take the exit Novo mesto / Zagreb. The motorway continues past Grosuplje and Ivancna Gorica. The toll on this section is 1.70 EUR / 2.60 EUR. The motorway section between Trebnje and Novo mesto is still in construction, so queuing traffic can be expected. Motorway continues after passing Novo mesto. It takes you past Krsko and Brezice and brings you to the boder crossing Obrezje (SLO) / Bregana (CRO). The toll on this section sums to 1.80 EUR / 2.70 EUR.