Let's disassemble what I just said, and try to reevaluate in terms of the environment. I mentioned two things: grass, and cars. Both have the potential to be put to better ecological use. "Being green" isn't always the cheapest or most convenient route, but it's always the most rewarding.
the scent of freshly cut grass : Have you ever considered a push reel mower instead of a typical Snapper or John Deere model? In this case, the push reel mower is the cheaper alternative, not only for the equipment itself, but also for all the cash you'll save on maintenance and fuel in the future.
I remember the first time I ever saw a push reel mower in my great-grandpa's garage as a young girl. I had to ask what it was, and when my dad told me, I laughed. I couldn't imagine a time when such ancient equipment was the standard.
But when you think about it, push reel mowers have a ton of advantages, not just as a cost-saver. My parents used to always complain when we lived in a compact subdivision that you could never go outside in the summer without hearing the roar of a lawn mower. Problem solved. Push reels are much quieter than a fuel-based lawn mower. You won't have to worry about little kids running around while you're outside working, so safety is a big plus. It's good exercise. And let's not forget thats it's pollution and maintenance free (other than occasionally sharpening the blades, which is a requirement for all lawn mowers).
Of course, there are serious disadvantages to a push reel. You can't be lazy and allow the grass to grow too long, because the mower will get bogged down. You'll have to commit to mowing the lawn when it needs it, instead of waiting two more weeks. If you have a lot of trees in your yard, you'll also have to rake up twigs beforehand; you can't just plow over them as you would with a mechanical mower. (*1) And of course, there's the feasibility aspect. If you have a large yard, and you don't have an Olympic team of push reels going all at once, it will take all day to mow the lawn. But the same applies for any push mower. Push reels are a fantastic alternative to regular push mowers, not necessarily riding lawn mowers. (Although, in case you were wondering, there is such a thing as a pedal-powered riding mower. I still can't help laughing at the concept, though I admire anyone with stamina enough to purchase one.)
If your bicycle and your push reel mower ever had a baby, it would probably look like this:
start rolling down the windows to enjoy the weather while I'm cruising around : What's more fuel efficient, rolling the windows down, or turning on the a/c? It depends on the aerodynamics of your car and the speed at which you're driving. For example, if your car is shaped like a brick on wheels *coughScionxB*, it's going to have a lot more drag than, say, a sports car. But since I don't know what kind of car you drive, I'm just going to focus on the second factor, which is the speed you're driving. If you're in stop and go traffic or driving at 45 mph and slower, it's best to roll your windows down. "The air conditioner reduces your car's fuel efficiency by up to 10 percent." Adversely, driving "at speeds over 55 mph with the windows down and you'll decrease fuel economy by up to 20 percent or greater."(*2) So 45 mph is generally the agreed upon transition between a/c and natural air.
Apparently there was even a Mythbuster's episode on the topic. The Mythbusters Adam and Jamie calculated the difference between open windows and a/c, based on a computer model. The computer said that the air conditioning was more fuel efficient. They put it to the test by both driving SUVs, Adam's with the windows down, and Jamie's with the a/c running. They both had 5 gallons of gas in their car and both drove at 45 mph. At the end of the race, Jamie's (a/c) car ran out of gas first, and Adam's made an additional 30 laps around the track. (*3)
In order to help our planet, we're going to have to unthink a lot of the standards of the society we grew up with, and start rethinking in terms of sustainability.