The house mouse (Mus musculus) can at times be harmful rodents; they are carriers of more than sixty infectious diseases spreading them through their parasites and feces. They can transmit pathogens that cause diseases such as salmonellosis, a form of food poisoning. In North America, breathing dust that has come in contact with mouse excrements has been linked to Hantavirus, which may lead to Hantavirus Pulmonary Syndrome (HPS). So ensure you have the appropriate PPE (Personal Protective Equipment) gloves, masks, goggles and coveralls.
Remediation of odour, cleaning, sanitizing replacing components affected by the rodent to include ventilation system and cabin air filters.
Spray down with disinfectants and HEPA vacuum any droppings or materials they have contaminated. The danger from infection comes from mice droppings (feces) which look like black peppercorn and about 0.12 in long, and have a strong musty smell, its urine, which can be seen with a black light, a strong odor is more likely caused from decaying matter especially if the rodent has died.
Rodents are carriers of more than sixty infectious diseases like hanta virus and persons cleaning should wear PPE (Personal Protective Equipment) gloves, masks, goggles and coveralls, and not stir up droppings or materials contaminated. Spray down with disinfectants and HEPA vacuum any droppings or materials contaminated
Rodents due to their size (3or 4 inches long) are able to squeeze into many small places where they leave droppings, urine or nest and sometimes die. The areas to check would be the engine heat shield, exhaust pipes, heater box opening, and glove box, under dashboard and seats, door storage, the center console bumper covers and the trunk.
The odour is more likely caused from urine and / or decaying matter
Proceed to remove plenum cowling from around windshield and then clean and disinfect entire area and parts. Fog a/c ventilation ducts with disinfectants, remove cabin air filter and disinfect housing, when decontamination is complete replace cabin air filter with new.
Check behind heat shield for nests or decomposing matter, check the interior compartment, under seats to include trunk for any sign of droppings, or nests. Check electrical wiring for any damage.
Inspect all interior areas and under seats and include trunk for any sign of droppings, or nests and / or decomposing matter. Check electrical wiring for any damage. Once all areas have been checked, cleaned and disinfected, treat for odor with appropriate chemicals. When you have finished cleaning go over all hard and soft surfaces with Lysol disinfectant or a vapour steam cleaner.
Inspect all interior areas and under seats and include trunk for any sign of droppings, or nests and / or decomposing matter. Check electrical wiring for any damage. Once all areas have been checked, cleaned and disinfected, treat for odor with appropriate chemicals. When you have finished cleaning go over all hard and soft surfaces with Lysol disinfectant or a vapour steam cleaner. (See also Odour, Mould and Smoke Control article).
Accumalator - I like the idea of a Havahart® Small 1-Door Easy Set® Trap
And the area between the gas tank and the bodypan (guess how much replacing fuel evap lines on an A8 costs 
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