US authorities planning closer estimate of car mileage - Page 2 - GreenHybrid

innergwave · #11 (**permalink**) 01-12-2006, 09:40 PM

I guess everyone on this site will soon be hypermilers!

Schwa · #12 (**permalink**) 01-13-2006, 02:57 AM

Quote:

Originally Posted by fernando_g

Speaking of A/Cs... I don't know if you have ever seen LP gas fridges, that were popular in the non-electrified rural areas during the 50s (it shows my age).

Basically the fridge with a small LP gas-fueled flame would heat the freon, and thru some thermodynamic magic would convert that heat to cold for the fridge.
Several years later in college, I asked a physics professor, with a PhD in thermodynamics, to explain that to me. True of most people with PhDs, he explained it to me using higher math that for him was both obvious and crystal clear, but to me was as understandable as IIIrd-dynasty Egyptian hieroglyphics.

Why is this anectode meningful to this thread??? Because one thing he did mention, and that I could understand, is that all the waste heat coming out from an automobile's exhaust COULD BE USED FOR THE SAME PURPOSE.

Think about that, A/C essentially for free, from the fuel efficiency point of view.

You can still get a fridge that runs on LPG (or electricity) for campers and RVs. I remember reading about them briefly, I think they use ammonia, boiling it with the burned fuel.

It probably could work with the waste heat from the exhaust of a gasoline engine.

subnivean · #13 (**permalink**) 01-13-2006, 07:14 PM

I read somewhere that they (the EPA) anticipate the highway ratings would go down 15% for both hybrids and non-hybrids, and for city it would be something like 30% lower for hybrids, 20% for non-hybrids. If you apply those reductions to the current EPA estimates for the corresponding versions of the Civic, the numbers make sense, imho. Anyway, I whipped up a spreadsheet, and while I won't bore you with the details, the hybrid came out looking even *better* with the new numbers, like 5-10% better than before assuming a 50/50 hwy/city split. Even if you skewed toward city driving, like 90%, the hybrid only lost about 2-3% of its current advantage over the non-hybrid.

Having said that, I think people like to be 'shocked' and will only see the larger absolute drop in the hybrid numbers, and there will be lots of 'told you so's directed toward hybrid owners based on that.