His pleas came as Ineos revealed 75,000 people have registered an interest in buying a Grenadier.
Ineos says the Hambach factory can make up to 30,000 cars a year by 2026, although it could produce as many as 50,000.
Mr Tennant also set out the network to sell and support the Grenadier, having already signed up several automotive dealer groups and plans for 200 outlets worldwide by next summer.
Dealers will support the car with servicing and parts, helped by giant German components group Robert Bosch, with Ineos able to access its global network of vehicle service centres.
JLR said the Land Rover Defender’s “unique shape is instantly recognisable and signifies the Land Rover brand around the world, with the classic shape being trademarked in many key markets. Protecting our intellectual property is something we take very seriously.”