You can't fight global warming when you drive a fossil fuel car. Right?

You fight Global Warming 'better' by not burning a lot of fossil fuels Than by burning a lot.

But the more active Global Warming fighters actually need a SUV with four wheel drive, etc to get out in the wetlands or wherever else they need to go to gather documentation for global warming damage.

Sure you can.  It's like losing weight while eating ice cream daily. 

I agree with Jakoba - unfortunately we are not yet at the stage where non-fossil fuel cars or anything else is a realistic option... we have little choice at this point really... but we can do things to reduce the amount we use and we can help fight it in other ways

You can if you burn used veggie oil.   You're not fighting it,  but you're fairly carbon neutral.
You're only burning surface carbon.

People who accept the solid science behind anthropogenic global warming are not necessarily advocating for going back to a pre-industrial zero-net-carbon-emission economy.

But anything we do  to mitigate it can help. Drive less. Drive a smaller, more fuel-efficient car. The next time you need to purchase a car, purchase a used diesel car and fuel it with bio-diesel fuel. Insulate your home. Shut off lights in rooms your not using. Live closer to where you work. Take public transportation when possible. Etc., etc., etc.

The problem is such behavior has to be a COLLECTIVE decision. If it's an individual decision, all my personal attempts to reduce my fossil fuel consumption do is lower demand for such fuels, which causes the price to go down, which ENCOURAGES others to consume more. It's not preventing AGW, it's simply cross-subsidizing someone else's fossil fuel consumption.

That's why I got an itty bitty car. Actually I only got it because it's so darn cute, but that's the excuse I like to use..