I used pepsi max as I prefer it to diet coke. I know it sounds like it would be expensive but I get worcestershire sauce in home bargains and balsamic in Lidl where its about £1 a bottle. You can use the red, rose or white one the taste is the same don't use expensive balsamic vinegar of modena though it would be a waste.
It's easy to make just put everything in a saucepan and simmer until it's thick. I keep it in the fridge and it stores very well keeps for at least a month but it usually doesn't last that long!
Cola BBQ sauce
2 floz worcestershire sauce
2 floz balsamic vinegar
1/2 tsp salt
1/2 tsp pepper
1 tsp dry mustard powder
1 tsp garlic powder
1 can diet pepsi or coke as you prefer.
Put everything in a saucepan and mix very well, Bring to a boil then simmer until tomato sauce consistency.