Some of the lesser-known downsides of motoring adventures can really sting.

You know that innocent civic hauler that’s chilling in your driveway? There are things about driving it that may be a bit, shall I say, unexpected.

How so? Well, for one “Only about 14%–26% of the energy from the fuel you put in your tank gets used to move your car down the road, depending on the drive cycle. The rest of the energy is lost to engine and driveline inefficiencies or used to power accessories,” says a study by the US Department of Energy.

Maybe not news to some, but this surprise is disappointing me, more so than not having cup holders. Or not having my VTEC kick in.

Air conditioning can also be a big leech. “Operating the air conditioner on ‘max’ can reduce MPG by roughly 5 to 25 percent compared to not using it,” says the same U. S. Department of Energy study.

Fuel efficiency losses may not be the only surprising thing about your rad motoring adventures. Something that a talking lizard may not tell you: insurance companies weigh and keep track of more than just the type of the car you have (sedan versus sports car for example).

Some things that go into consideration are cost of repair. Think how much it costs to repair a Ferrari versus a Honda Civic, for example. Vehicle features, particularly safety features, and of course your age and sex are also considered. Then there are also things like your location (is crime high in your area?) and your credit score.

Well now, there’s the wisdom behind the Carfax.

Some auto surprises may be more benevolent, of course. See, your ride may share more with other cars than just belonging to the horseless carriage kind. Like, the Mercury Sable in my backyard, if I can’t find parts I need for it, I am pondering appropriating some from a Ford Taurus.

The benevolent part is that doing so is certainly cheaper than special ordering or going to a dealer. I do have to pay attention to things like production year of the car, condition of the parts and which parts are actually interchangeable. But that’s okay; even if it means a little bit more work (doubling-or in case with some cars, quadrupling), the list of potential donors is nice and worth the trouble.