Interesting topic . . . and very timely.
First off, as some other folks have stated . . . for me geocaching is a hobby and as such a discretionary "line item" in my household budget . . . but when I stack this hobby up against ATVing or sledding (costs to register, fuel, eating out, trailering on occasion, etc.) it seems as though geocaching is a real bargain . . . more importantly the benefits for me outweigh the costs (i.e. the views, getting outside, getting some exercise, meeting up with friends, etc.)
That said . . .
1) I've been opting to run my new "beater" car . . . it's not a real beater car like my old 1990 Celica, but nevertheless the Honda does get pretty comparable gas mileage and is a heckuva lot better than the gas guzzling 4Runner. Honestly, I prefer the gas sipping Accord better . . . except when my stupid Magellan takes me down a gravel road with washouts . . . major washouts . . . in the middle.
2) I intend to see if folks might want to partner up and car pool . . . and I should add that other than grabbing local caches near home or at work I tend to wait and do a day or a weekend of caching rather than running out for an evening of caching. For me caching is a real treat and so I tend to go out on just one or two "big" outings rather than lots of shorter ones. Usually I try to combine these outings with camping . . . that way I get a "two-fer" . . . well "three-fer" if you're able to go caching and camping with friends.
3) I often skip meals while caching . . . I know, I know . . . sounds hard to believe. However, this past weekend I tended to snack more than eating real meals . . . although I did run into Parmacheenee while eating my "lupper" near a cache site. I also try to pack drinks in coolers and often stock up on water (even though I'm not a big water drinker) when I find free tap water at parks, springs, etc.
4) Like Squirrelcache said . . . plan out the day. Don't rely on the "caches closest to you" feature on the GPSr -- oftentimes that will direct you to go one way and then the next. Instead use good software or at the very least take a look at gc.com's google maps and plot out your trip.
5) Like Vicbiker said . . . I often look at cache density when choosing where to go on my caching adventures since I'm a pretty busy guy and I honestly don't want to drive several hours to find just one cache (that's just me . . . and my opinion). However, I also don't want to spend all day looking for GRCs and LPCs . . . I tend to pick a location farther from home in a place that looks interesting or with caches that sound scenic, historical, etc . . . so density plays a part for me . . . but it's density + location that really matters (i.e. one reason I went to Eustis last year was due to the fact that a particular gcmainer had put out a lot of caches in an area that appealed to me . . . and there's another gcmainer that put out a bunch of caches in the Abbot area a few weeks back that I noted would be good to check out.)
6) Finally as Native Mainer mentioned . . . I also will try to incorporate caching into my commute . . . but eventually you either reach a point where all you have left are new caches in the area or you end up driving 1 1/2 hours and 66 miles to work for what is normally a 45 minute and 33 mile commute . . . but ah, at least I can justify it to myself . . . it was technically on the "way to work."
"Courage is not the absence of fear, but the realization that there is something more important than fear."
"Death is only one of many ways to die."