Have blue liquid drips in garage, thought it was the windsheild washer liquid. Dealship indicate probably coolant (is Mini coolant reallly blue?) and thermostat could be the issue as it is a known problem. Dealship would have to pressure test but talking $500 ... do they need to take of the Turbo or something?
Since you have mentioned before in other posts you have a 2007 Convertible, assuming it an S model you have a Supercharged engine. Thermostat housings are known issues on these cars. Where on the floor under the car is the blue spot located?
Ahhh the old smurf juice on the garage floor. Yes the Mini/BMW coolest is Blue. I would try and find a Mini shop that is not a dealership and have them replace the thermostat gasket and housing. Please post more information about your car and your location and people will be able to assist you with more Non-Stealership locations to have your car serviced.
Just found this problem on my '08 Clubman S. Found where the thermostat was leaking around the housing. Housing looked to be fine, not sure I needed to replace it but now that it's off it's getting replaced. Another time I'd try doing just the thermostat first and see if that fixed the problem since the housing is over $100, ouch.