I took a tape measure out to the garage. From the garage door to the oposite wall is 20 feet. There's about two feet worth of boxes and things piled up in front. So, that's 18 usable feet of space. The garage door is 16 feet wide, so 8 feet per car.

18x8 feet = 216x96 inches.

The Acura TL is 189.3 x 72.2 inches, giving me a margin of 27 inches, front-to-back and 24 inches side to side -- basically one foot of space on every side, if you park it absolutely perfectly. A TSX is six inches shorter and three inches skinnier -- not really different enough to make size be a defining issue between those two choices.

Interestingly, the Volvo S60 is 180.2 inches long and 71 inches wide (much smaller than I thought). The Volvo S40 is 176 inches long and 70 inches wide. A Saab 9-2X is 175.6 inches long and 66.7 inches wide. A Lexus IS300 is 176.6 inches long and 67.9 inches wide. I guess the question for me and my wife is whether one foot of margin, all the way around, is enough or whether want the extra margin of a shorter car. Hmm... I wonder whether these width numbers include the mirrors?