Really for me it depends on the situation as well, I normally do not intend to tailgate someone, usually I'm not paying attention to the distance or about to merge, but I WILL intentionally tailgate if the person is in the fast lane and will not merge, typically with a flash of my high beams as well, NOTHING pisses me off more

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The Present:
2014 Audi Q5 TDI Prestige
The Past:
2013 Lexus GS350
2013 VW Golf TDI
2007 BMW X5 4.8i LOADED & Loved
2009 VW Jetta
2008 VW Touareg VR6
2005 BMW X5 3.0i
2005 BMW Z4 3.0i
2004 BMW X5 3.0i
2003 BMW 325i
2000 Ford Explorer Eddie Bauer 4x4