Then get a diesel or a motorcycle. Both handily beat hybrids and cost way less.
Simply not true. Most diesel autos offered get measurably worse mileage than, say, a Prius, and this on more costly (diesel) fuel at that.
And even many, many motorcycles get worse gas mileage than a safer, larger, all-weather, 4-5 passenger plus significant luggagecarrying Prius.
I would have expected a better grasp of the basic facts from you, Dave!
First, I was replying to shortylickens post which seemed to be to complain about raw mileage only, not safety or all-weather, passenger count, or luggage carrying. In all of those, a car obviously wins. But so does a freightliner. But changing body style drastically effects everything besides raw MPG in the equation. But that's ok, we can take that out. Hybrids don't do what people think they do; in almost every case a diesel engine would be more fuel efficient and cheaper over the life of the car. But the US population generally hates diesels for reasons that they, themselves, don't understand. So lets look at some examples.
lets look at a car first instead of motorcycles. Here is a perfect example that I did absolutely no research on besides the fact that I know some VW's can be had in a diesel while the body is nearly identical. We need to remove all variables as possible in order
2009 Volkswagen Jetta Sportwagen
Diesel: 29 mpg City/40 mpg Hwy with 140 HP/236 ftlb torque
Gas: 20 mpg City/29 mpg Hwy with 170 HP/177 ftlb torque
A 32% improvement in city mpg and a 38% improvement in highway between gas and diesel in the same car. If that isn't 'handily beaten', then I don't know what is. It would be a perfect comparison if VW had a hybrid model, but sadly they don't. If I was really bored (which I am not) I would do some math to compare the cost of diesel to gas to get a mile per dollar of fuel, then add the price difference of the diesel option, and figure out the maintenance differences for this car. But I don't really feel like it, since I have done it on other cars and already know the result. Hell, the Prius 'actual' mileage is only mid 40's.
If you want more examples, top gear has dome some races on their track between diesel and gas cars, and the results would surprise the hell out of you based on your comment above. Diesel has more energy in it per unit weight, and a diesel engine is able to extract more of that power and put it to the road. Both combined lead to an equivalent diesel beating the crap out of an equivalent gas car both in performance and in economy (MPG or MPD, however you want to calculate it).
The diesel is actually 50 state LEV II emissions rated, which means it is likely cleaner than your car. It is definitely cleaner than mine. It will even run on biodiesel. That means fuel can cost as little as $0 per gallon (plus filtering and such, which raises it to about 50 cents per gallon). It would be that price for me since a friend runs a mexican food joint. He would probably pay me to take the oil instead of disposing of it. I don't get that diesel is more expensive than gasoline. It isn't around here, diesel is usually within a few cents (higher or lower, it fluctuates) than 87 octane gasoline. I don't know if that is true nationally though.
Since you say most diesels get lower mpg than a Prius, then please, post some data. Show me a diesel that weighs close to what a Prius does with equivalent performance numbers where the prius kills the diesel in MPG and I will eat crow. It should be very easy since 'most' means > 50%.
Your motorcycle comment makes no sense. A quick look shows the yamaha vstar classic with 50 mpg and performance numbers that leave the prius in the dust. To get horrible mileage you need a big ass motorcycle, like maybe the roadliner, but even that gets 42 mpg. Almost every motorcycle (unless you get into crazy displacements < 250 or over 1500cc) are between 40 and 60 mpg. You can get > 100 MPG on a < 250cc motorcycle if you try.
sources in my 5 minute search:
http://www.motortrend.com/roadtests/oneyear/112_0902_2009_volkswagen_jetta_tdi_arrival/index.html
http://www.automobilemag.com/reviews/sedans/0310_toyota_prius/index.html
http://www.eurocarreviews.com/specifications/volkswagen_jetta-sportwagen_2009_4dr-2-5l-s-auto
http://www.autoblog.com/2008/05/04/first-drive-2009-volkswagen-jetta-sportwagen/
http://www.vw.com/jettasportwagen/en/us/
http://www.automotive.com/2009/12/toyota/prius/specifications/exterior-aerodynamics.html
http://www.thetruthaboutcars.com/2009-vw-jetta-sportwagen-se-review/
http://www.hybridcars.com/emissions-standards.html
http://www.brianberliner.com/2007/02/2007-toyota-prius-mpg-actual-results/
http://www.popularmechanics.com/blogs/automotive_news/4257807.html