All of the complex attributes of the road cars are for naught in X-Com: Apocalypse because one shot to the road will blow out that section, and the car (which is unable to stop) will inevitably be destroyed as soon as it goes off the road. These roads are pneumatically operated and the cars actually hover slightly over the road. I don't think there's a problem with them not being able to stop. But the roads should be a lot more durable. I can't remember the last time a stray shot tore up a section of tarmac in real life. Just mentioning this.