yes. yes it is. I got up to a million bucks by diving right in front of a semi which caused a huge pileup and my character was wedged between two vehicles and racked up money like crazy. Jumping in front of a train is another good way to get mad points.
The best ways are to be in a cop car since it adds a 4x multiplier automatically. There are certain ways to hit yourself.... and the best ways are to hit walls at a certain speed... hitting a certain sweetspot. 1m-6m was uncommon.... but doable with a certain amount of consistency. My brother though... he had something along the lines of negative 2.4 billion from a hit that kept him flying upwards until he died.
Yeah... we took turns doing the whole insurance fraud thing. Although cop car+ wall gave the most money, getting on the highways (especially in tunnels) and crashing/ jumping into semis was the most funnest. Especially when the pile ups are all dramatic like with 40 civilian deaths and such.