To be honest, if you think F1 has no passing, you didn't watch a race this past year. Yeah, some of it was aided, but there were some races with more passing in one race than the entire previous season. Some were still dull as shit (lo and behold Tilke-designed tracks), but some were great.
However for proper wheel to wheel action, sports car, BTCC, WTCC, World and British Superbikes, they are all where it's at. The problem at the very high level of motorsport (F1 and MotoGP are prime examples) is that the drivers are very, very refined, as is the equipment.
Good examples are looking at Nigel Mansell making IndyCar look like a joke in 1993, Barrichello doing Indycar testing this year and being as fast/faster than everyone else there at his first try, the fact that the past two World Superbike champions are ex-MotoGP guys who can't hang with the current crop any longer. Alex Zanardi couldn't make a dent in F1, yet won two CART titles, Montoya won at his first attempt, and then subsequently couldn't win a title in F1. Sebastien Bourdais was outpaced by a guy pretty much a decade his junior, and he won the CART title 4 years in a row. The same Sebastien Bourdais has been putting some of the LMP drivers to shame by doing times a second quicker in the same car. Anthony Davidson was a bit of an also-ran in F1, good but didn't even have the measure of Takuma Sato, the same guy who Jenson Button made look like an idiot, the same Anthony Davidson who put the Peugeot 908 on pole at Le Mans this year.
When everyone is that good, the opportunities to capitalise on mistakes just aren't there as often.