Mileage. Cars get up to operating temps fairly quick these days, due to emissions (the 2.5 mile commute might be the exception). I might be a little reluctant if it's a weekend only car that also sat through winters.
2011 Jerez Black/Fox Red E90 M3 DCT, ZCP, ZCV, ZCW, ZP2, BMW Apps
2004 VW R32 (track car)