When you're trying to live frugally, you can save on big-ticket items (a car, a house, a vacation, etc) or on smaller items (groceries, clothing, eating out, etc).
The savings you'll see if you buy a less-expensive car is far more than you'll probably see at the grocery store (I hope - maybe you buy really expensive groceries), but you'll probably go to the grocery store hundreds of times for every one car purchase, which means the savings you can get at the grocery store, while only a few dollars a time, can really add up over time.
One of the places I save a little money is with my home printer. We're not talking hundreds of dollars of savings here, but it is a place where we can cut costs a little bit with no real effort on our parts. We do this in two ways:
1) We realized last fall that 99% of our printing is done for things that don't require any particularly nice paper. It's just directions from Google Maps or grocery coupons or boarding passes for an airplane trip. Instead of buying packs of paper for a few dollars at Wal-Mart or the grocery store, we started hoarding all the paper that entered our house that was blank on one side. It became immediately obvious how MUCH paper we got. A calendar from church, a credit card offer in the mail, a letter informing us what precint to vote in. And then, we started bringing some home from work - the notices I got at school alone filled up our printer tray in a matter of days.
2) As I said above, we realized that our printing rarely needed to be high quality. Printer ink is fairly expensive, so we hate to waste it. We went on to our computer settings and changed the automatic mode for our printer to "Fast Draft," rather than high-quality. The quality is still perfectly fine - I have no problem reading anything and it's sharp enough for the scanners to read the barcodes on my grocery coupons - but it uses a fraction of the ink and, bonus, prints FAR faster and your paper isn't warped from all that ink. Win-win.
I'm certainly not going on a cruise with these savings, but it's less trips to the store and less money out of my wallet.