Why don't you wind down the windows a little and fix/tape some Musim/Net curtian type mesh over the openings? Lets the car breath, and keeps out the creepy crawlies.
Im thinking this is caused by a mix of Stale/static air and possibly the containt change in tempreture on the garage. If its been locked away over winter, then we have had -15 degree temps back in jan/feb ranging up nearly +30 degrees in the heatwaves of the last few months! can't be helping with the old condensation and sweating issues!