I questioned Eurotunnel on this and received the following response.
Thank
you for your email.
When you travel in this vehicle (Macan) please book it as needing "high"
space and indicate that your vehicle is above 1.85 metres in
height. We can then board you to the single deck carriages which are
much wider - they can take 49-seater coaches etc. Please follow the
routes on the terminals for high vehicles.
In the event that you are challenged by a member of staff asking you to join
another queue you must refuse and refer to this correspondence. Our
Customer Relations Manager is Lorraine Dilucia and she says she will be happy
for you to use her name if needs be.
you for your email.
When you travel in this vehicle (Macan) please book it as needing "high"
space and indicate that your vehicle is above 1.85 metres in
height. We can then board you to the single deck carriages which are
much wider - they can take 49-seater coaches etc. Please follow the
routes on the terminals for high vehicles.
In the event that you are challenged by a member of staff asking you to join
another queue you must refuse and refer to this correspondence. Our
Customer Relations Manager is Lorraine Dilucia and she says she will be happy
for you to use her name if needs be.