There have been a number of postings regarding using the World Mastercard in lieu of buying CDW especially in Ireland.
It does work - kinda.
I had an accident in Ireland scraping the car. I was charged 2000€ deposit for damage and eventually refunded 955€. Net bill 1045€. I filed the claim with M/C.
The damage cost was overpriced but you have to figure the rental car companies are going to charge a premium repair for the damage.
M/C claim took about 1 1/2 months. M/C was cooperative as was Thrifty and it was mostly handled by email with some calls by me to Thrifty in Ireland and M/C in the U.S.
M/C refunded the damage claim MINUS the VAT. They don't pay the VAT. 1045€ was about $1410. M/C gave me $1253. My cost was about $150
Net result was my cost for the damage (the VAT cost) was somewhat approximated the cost of super CDW - possibly 30% cheaper.
Would I use the M/C card in lieu of taking CDW? Not in Ireland. Too much chance of damage. Heck, I'd skip the car next time and use public transportation between cities and local outfits for tours to sites. But if I did rent the car there, I'd opt for the CDW and avoid the hassle although I did save money.