I'm not very proficient at calculus, but I did happen to craft my own theorem the other day:

As the upper limit of gas prices increases, personal insanity approaches infinity.

Unlike any of my limit problems in high school, I was actually able to prove this one this morning:  A 1993 Geo Metro sold for $7200.

One look at the trim (XFi) and the powertrain (1.0-liter I-3 and a five-speed manual) shouts why this car sold for such a high price: fuel economy.  The 49-hp hatchback, devoid of virtually every luxury imaginable, was able to return close to 58 mpg on the highway.  

That figure seems to be increasingly attractive at a time when gas has surpassed the $4.00-per-gallon mark.  Recent eBay auctions for similar cars have yielded transaction prices over $5000 - and easily 20 to 30 bidders fighting for the lithe hatchback.

But does 58 mpg really warrant $7200?  For a Metro?

That sale price is over the XFi's BlueBook value.  Way over; as in seven times over.  Popping over to Kelley Blue Book's website, we see the expected retail price of a used '93 Metro XFi - with 22,000 miles and no options, like this example - is $1100.  Mind you, that's for a Metro in mint condition.  This car had some bubbling in a rear fender, meaning it's in "good" condition.  We should be looking at $950, max.

Besides, XFi Metros never sold for $7200, even when they were brand spankin' new.  Some diligent digging in the Automobile archives produced the base price of a '93 XFi hatchback.  That sum?  A whopping $6795; tax, title, and exorbitant options (like a passenger-side mirror) not included.  Granted, inflation puts that price closer to $10,000 in today's currency, but should a base Metro depreciate by only 2 grand over 15 years?

And did I mention it's a Metro?  Although devoid of the stigma carried by the infamous Zastava (known and despised on these shores as the plagued Yugo), Metros weren't anything special, unless basic, stripped-down subcompact hatchbacks regularly frequent your fantasies.  They weren't devoid of problems, either; for example, the three-cylinder mills were prone to compression problems unless the EGR system was religiously cleaned.

I'm not criticizing the idea of downsizing a daily driver in order to save money.  However, there are better options.  There are plenty of clean 1996-2000 Civics - capable of highway mileage in the mid- to high-'30s - trading hands for similar prices.  Want to go new?  For less than double the money, you could step into a Toyota Yaris.  With a five-speed manual, that's capable of 29 mpg in the city and 36 on the highway.

Granted, you're not getting the 58 mpg promised by the Metro, but either gives you a car that can safely and comfortably carry four people - and still manage to get out of its own way when merging onto freeways.

Lest you think I've concluded human kind is carrying itself to hell in a hand basket, fear not.  I'm saving that reservation for when I see a Chevette Scooter fetch upwards of $4000 at Russo & Steele.