Oh great was my woe when we couldn't build proper steerable wagons anymore after update 0.6.0 more than a year ago! (You know, proper wagons as in rotatable front axle + pushing bar.) And how great is my joy that now with 0.7.x, it finally works properly again! I could build a wagon and pull and steer it with ease even though it was heavily loaded! No blocking axles, no drifting! I would even say it worked a bit too well.... Remember to lock your car, kids.