No Corvettes or other 2-seaters in the left lanes at all unless you bought the transponder option with the car. They don't call those things the Lexus Lanes for nothing.
By Federal Law, motorcycles are permitted in HOV lanes but if the HOV designation can be replaced with a tolling scheme, the motorcycles are booted out as well. Right now the extreme left lane on selected roads, formerly known as the breakdown lane, is HOV/Toll and fines are collected by camera. You'll get a bill for using the lane on your motorcycle because the software can't tell a 2 wheeler from an 18-wheeler, but you can use the lane for "free" if you buy a $35 transponder and attach it to your motorcycle presumably in a way that it won't get stolen.
I'm not sure if putting a child seat in the back of a pickup is actually legal, but at least it would be facing the right direction. If you have 2 kids and a standard pickup, both of them need to ride in the bed a la Subaru Brat as it's illegal for anyone to ride in a child seat in the front seat of anything.
At the rate we're going, in the near future, all roadways in Colorado will be toll roads unless you're transporting 2 or more
I'm also pretty sure that except for agency vehicles, nobody who works for the Colo Dept of Transportation actually owns a car.