Add ons basically means what extra things you have taken along with comprehensive insurance.
Zero depreciation , consumables cover etc are add ons.
Please check this link here for detailed explanation "Car Insurance Add-on Covers"
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Who's your agent ? Suggest you to ask for insurance premium from another agent or maybe try online to get another quote.
Also you should ask your agent to give you information regarding the add ons you have.
Ps : I generally go for zero depreciation + consumables cover + engine and gearbox cover.
I will give you an example.
Say someone's car gets into an accident. There is major damage to the front, coolant is leaking and even engine oil is leaking because of hit from the underside. Now that's a major expense if you don't have zero depreciation add on cover.
If you have zero depreciation then you just need to pay the file charges which is just under 2000rs for any car but you have to pay for coolant , engine oil etc.
If you have consumables cover, you won't be charged for refilling of coolant and engine oil.
Say the car keeps on running for some reason and the engine gets damaged because of no engine oil then with the engine cover you don't have to pay any charges for engine replacement.