BTCC rear camber

Hello all. I was watching BTCC over the weekend and noticed the majority of the FWD cars where running a lot more negative camber across the rear axle compared to the front. I'm just wondering what the reason is behind this. It seems counter intuitive as id expect this to give an understeer characteristic which id assume most drivers wouldn't want

It depends on the rear K & C and it's relationship to the front. It may be that they are treating the rear of these cars like it has a solid rear with a spool center, where you want the inside rear wheel lifting in cornering to reduce the push generated by the spool and get it to turn in.

Having more camber on the rear when rolling presents more tyre surface when it is needed, but also reduces the contact patch size in a straight line, potentially reducing drag by a small amount.

Its been months, but I'll add to this:

Too much camber also takes away grip, so it can still be used as a tool to subtract grip and adjust balance. The benefit here is that when you jump a curb, the car doesn't get as upset as it now can use the tire correctly.

Camber also gives stability at the expense of rolling resistance. You get something called camber thrust, which can be quite significant, but this also means induced drag and higher rolling resistance (no force is free when it comes to tires). A car with 3 degrees of camber will probably get to 3-5mph more on a decent straight than the car with 5 degrees, but one of them could exit the turn leading up to the straight quicker and make up that difference.