没有什么大语病,有一个词用的不恰当,试试把gap 改成 ditch,并用复数.ditch:a long,narrow excavation made in the ground by digging,as for draining or irrigating land; trench.
gap:a break or opening,as in a fence,wall,or military line; breach:We found a gap in the enemy's line of fortifications.
就是说ditch才是指地上的沟.
补充：
1.重新查了一次汉英字典,沟：ditch/gully,其中ditch比较常用一点.gap的中文是裂缝/缺口.所以我还是坚持用ditch.
2.同意用handle the difficulties.solve the problems是解决问题的意思,离原意有一点远.
3.with the car can cross over...绝对有语病.
4.cross over 有一种过到马路或河的另一面的意思,建议用drove over.
here is my try:他不断测试小车的性能,改进小车的结构,终于解决了所有的困难,小车可以平稳的越过障碍和沟.
He kept on testing the performance of the car,improving its structures,and eventually handled all kinds of difficulties.The car drove over the obstacles and ditches smoothly.