truma gas water heater

It's not advisable to have your gas on when driving, but some do it. The blown air heaters that use diesel or petrol can be used when driving.

i found this on the turma website
"Yes. With Combi and Trumatic E heaters, the heating function can be used without a problem whilst driving.
In the case of Trumatic S heaters, however, the heating function can only be used together with a cowl top, which must be installed freely in the air flow. Truma recommends cowl top T3 or cowl tops T1 and T2. Otherwise, the flame may burn back and cause damage to the heater.
Additionally, the cowl top must protrude at least 10 cm beyond any additional roof accessories (roof boxes, ski racks, luggage racks, etc.) so that the heater can function without problems.
You can find out more about safe heating whilst on the move here."

i would have said no myself

Older vehicles work in non compliance, whilst new vehicles must have a crash sensor system, or even drive safe, also some older heaters must have flue extensions and air intake extensions, if truma contact truma/uk if alde contact alde