Trust me not to go for the obvious
I twigged the "Half a Maunsell" bit as soon as you mentioned your half share in the carriage but I couldn't for the life of me work out what corKtina had to do with Maunsell or carriages

Was "cor" short for corridor? Was "K" the code for composite? Surely "tina" wouldn't feature in anything to do with railway carriages.
After a sleep and a quick look through the Irish car forums I now assume that it's yet another play on words but this time featuring Cork and that good old "horseless carriage" the Dagenham Dustbin.
I should have realised.....you've mentioned your car collection often enough