Problems with a nearby sewage plant are costing MK Seat in Milton Keynes in terms of lost productivity.
Cliff Freeman, director of the dealership, said the smell was so strong that workers complained about feeling sick and even refused to come into the office.
He said: "When the wind is blowing in this direction it can be quite awful and obviously now leading into summer it is becoming unbearable."
It's not the first time the dealership has suffered. Freeman previously complained to Environmental Health years ago.
The stench has also been noticed by neighbouring dealership Stratstone Jaguar, where sales team leader Paul Parkhurst told the Milton Keynes Citizen: "Winter is not a problem but this time of year it can be a nightmare."