Hybrid Vehicles/MPG

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QUESTION: This isn't specifically to do with hybrides, but I was wonder if it is easier to design cars with higher highway MPG than city MPG? I used to have a 2000 Mitsubishe Mirage which until its unsightly death gave me 25 or 26 miles per gallon, but now with a much more recent model, a 2008 Elantra I seem to only get 23 or 24 MPG. 25MPG once after just recently filling the tires. But otherwise the car boasts 38 MPG highway, which is all fine and good, but I mostly drive in the suburbs. Which is easier to get, city or highway MPG when designing cars? And why shouldn't my car of 8 years younger be much more fuel economic?

ANSWER: Many of the recent gains in fuel economy have come from streamlining, which has a much greater effect on the highway.  In the city, the economy gets worse even with less air drag because the machinery is being used inefficiently, and wasting energy on the brakes, etc.  A hybrid does better at meeting the fluctuating demand efficiently, and may even recover some brake energy.  
If economy were the prime consideration, we would be getting hundreds of miles per gallon, but people buy a lot of extras, and companies love to promote them. The pressure from market forces has often halted progress on economy.  To start to take matters into your own hands, check out http://ecomodder.com/  Just changing your driving style can help a lot, and there are tips on the best tires, etc.
Thanks for taking an interest,
Bob

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QUESTION: Is there a list of cars that get the best MPG in city/suburb situations (and hence probably good highway as well)? It just really seemed that spending twice as much on a car that is 8 years younger than my old car, and knowing the fuel economy regulations have been steadily changing, that I should have ended up much better. :(

ANSWER: The home page at ecomodder has:
Best non-hybrid MPG: 2014 Mitsubishi Mirage?
Mitsubishi says its new Mirage subcompact will get the best MPG of any non-hybrid: 44 mpg (US) highway, 37 city. (Some drivers are already beating that in various economy driving contests.) How? An efficient 1.2L, 3-cylinder engine, very light weight and aerodynamic design.

I'm not sure if there is a list that is sure to include the most suitable vehicle for your needs, but it is easy to check and keep notes on those that interest you.  You can also save thousands of dollars by buying one of the older, high MPG cars.  I get an easy 40 MPG for $200 per year in combined parts and depreciation, and a bit of time.  

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QUESTION: What parts are most responsible for differences in MPG, and would it be efficient for cars to offer 2 models at slightly different prices of each model? One high MPG in city, and one for highway? Also isn't there a simple item (for maybe $50 tops) that people sometimes insert in the air pass of their cars to increase MPG by whole number? I saw something like that on TV a while back.

Answer
It isn't unusual for cars to be offered with two or more engine options for economy or power.  Diesels and Hybrid options are best for highway and city respectively, although the diesel is quite good in city use as well.  
Aftermarket accessories for MPG gains are often a scam, but you can get a couple of MPG just by running your tires at their maximum sidewall-marked pressure, instead of the car manual's recommended PSI.  If you won't be blasting across a desert in the summer, you can run them quite a bit higher.  See Ecomodder for that discussion.
You could probably dive in to the automotive literature almost anywhere to get a start on such basic questions as what parts affect economy, and how.  It is a huge topic.  

Hybrid Vehicles

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Bob Stuart

Expertise

I'm best on questions of the suitability of new technologies, but will try to keep up with retail offerings of hybrid vehicles too.

Experience

Designing human-electric hybrids.

Organizations
International Human Powered Vehicle Association

Publications
4th Annual Velomobile Seminar proceedings, many listserv postings.

Education/Credentials
few academics, but my 1st prototype won a world championship, and I've lectured to engineers.

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