I have recently returned to caravans and over the last 1000 miles there has been a loud bang from under the car on three occasions when towing in town at approx. 20 mph. The towbar has been inspected and is ok. The bump stops are in place to cushion spring compression. Has anyone encountered this.

Welcome to the forum Mike, you'll find the members on here are a friendly and helpful bunch 🙂

When you say it happens at slow speed in town, Is it whilst traveling straight or around a corner? Is it over speedhumps or not? 

have you had the car on a ramp to inspect for any damage or checked the caravan underneath?

cheers

Steve

Could possibly be where the additional drive (AWD) is kicking in as the load is applied (assuming yours is equipped with the AWD option).

I get a 'clunk' as the AWD kicks in on my CR-V and although not violent, it is noticeable and at least it lets you know it has shifted drive.