If a question is asked explicitly on the claim form, you need to answer it honestly, otherwise, apart from other considerations, you risk invalidating your claim.
Why do you mention the Revenue VRT calculator in arriving at the value of the car? That will have little effect on the insurance company's valuation of the loss. What value did you declare for insurance purposes?
In my experience, they will arrive at their own valuation anyway, based on some obscure underwriting magic .they do internally.
One of my cars was written off in an accident and in settling the claim against the 3rd party, the insurance company valued the wreck at 5,000 for salvage purposes and deducted that from my settlement, having already reduced my valuation on the car to their version of "fair market value".
"Ours is not to reason why, ours is just to pay and pay and pay and pay..."
Sorry to hear about the loss of your car and the insurance company will probaby remit at least part of the claim to the finance company.