Hypermiling a V6/V8?

[RollerCoasterofLuv]

So far, using mild hypermiling techniques (coasting in neutral, driving slower, and being smart about acceleration/braking) I've managed to get my '96 VW Golf GL to consistently pull 35-40 mpg in mostly highway commuting. That's roughly 50% over the revised EPA estimates of 22 city/28 hwy.

However, I'm just plain sick of the car. It runs fine, but it's showing its age and needs some maintenance I don't want to invest in it, and, shallow as it is, I'd like to get something a little less "dorky," but still consistently get 30mpg+ without doing anything fancy or stupid.

I'm thinking of maybe a larger vehicle like a Jeep Wrangler or Cherokee, a full size pickup truck, or maybe even a rear wheel drive muscle/sports car like a Mustang GT (I would go V6, but Ford 4.0s have serious design flaws) or maybe even a Nissan 350Z. These are very different types of vehicles, I know, and all I really need is basic transportation, but I've always had my eye on them and I'm getting sick of driving cheap nerdmobiles with no style or power.

My question is if I were to get a car that's a bit of a guzzler, would I likely still be able to get the same 50% over EPA in it? I know a bigger engine would use more fuel in idling, but it also wouldn't need the 3000+ rpms my painfully low geared Golf needs to achieve interstate speeds.