It's a deadlock situation and can arise without any screw ups. Imagine the buses being 5x as long and all reach the intersection at the same time as an example. All have space to enter the roundabout but they'll reach the same situation as in the picture.
To fix this people uses signals and can be done by having the buses follow "Only 1 or 2 articulated (double) buses are allowed into the roundabout at a time". A rule like that might be required if you have a lot of articulated buses. The risk of this happening depends on how many ways you can enter a roundabout no a bus like that, how long the buses are, how frequently they run and how big the roundabout is.
You can charge the plugin hybrid and do your daily drive (~50km) on just electricity. Hybrid cars are just a way to save some fuel with regenerative braking and charging on a downhill.
PHEV is great if you have a monthly/weekly trips that are longer than 100km where you use petrol or if you want the option to drive 500km road trip without an hour long charging break. This is very good for people that have a charger at work but live in an apartment that they can't charge the car.
HEV is going to be cheaper than the PHEV since you have a lot smaller battery and electric power system. The electric system is only there to take a load off the ICE engine and can potentially make it last longer by not having it run at a lower intensity.
As soon as you can charge the car at home EV is the best, people should take a break from driving every 2-3 hours anyway for safety on road trips. Downside is that you need a charging station to drive of course. EVs can potentially be the cheapest of the bunch since you only need one system to propel the car forward and battery prices are falling.