The new rules for the 2012 Formula 1 season have resulted in uglier race cars with nearly all cars sporting a unsightly hump on the nose. Here is an overview of the most important rule changes:Stepped nose: Starting in 2012, the noses of the race cars must be lower for safety reasons. Nearly all the teams decided to use the uncommon-looking form of a hump or stepped nose to make the new nose more aerodynamic.Technology tricks: The so-called blown diffusers are banned for 2012. This trick with the exhaust tailpipe was considered one of the reasons for the dominance of Sebastian Vettel's Red Bull team last season. The teams' engineers are desperately looking for loopholes to improve the aerodynamics of their cars.In-season tests: Once again, one three-day in-season test will be allowed. All of the teams will be testing their race cars in early May in Mugello, Italy. In-season tests were banned in 2009 for financial reasons.Crash tests: Starting this season, race cars must pass all crash tests before being allowed to start at official on-track testing. All have done so.Race length: A GP will last for no more than four hours. That will ensure suspended races can go no longer than, in theory, eight hours. The 2011 Canadian GP lasted four hours and four minutes, a record.Racing lines: Drivers defending their position can now only alter their racing line once, as they are no longer allowed to retake their previous line. In addition, drivers will not be allowed to leave the track without good reason, thus banning strategic moves such as cutting chicanes during in-laps to save time and/or fuel.Safety car phase: Starting this season, lapped drivers cars can unlap themselves during a safety-car period. This will prevent back markers hindering the leaders at the restart. In addition, cars in the pits when a race is suspended will be allowed to reclaim their previous position in the race.