Well, it’s been a year (plus two weeks) since I started keeping a spreadsheet on the 2005 Toyota Prius I bought from a friend. I have tried to fill up at the same pump at the same time of day. Obviously this isn’t always possible.
This morning my calculated mileage was 51.50 mpg, and the indicated mileage was 50.6 mpg.
Average miles per gallon as of this morning is 47.12, with an average 3.08% error between the indicated and calculated mileage. (Calculated is usually lower.)
That’s certainly impressive. I’m glad you’ve got an R1 for the fun miles, though. 
I’ve got a VW Passat as a company car. Boring as an accountant, but does what it says on the tin. Mileage - don’t care, it’s not my bill. But in the weekends, I don’t mind a little fun when it comes to driving. I’m not even going to convert the kilometrage of a '95 Alfa Spider V6 into imperial - it’s not like I care about it in metric. About 4 Priuseseses?
Bottom line is, it’s fun. I fill the tank when it’s empty. Take her to the specialist when she’s sick (which is frequently) - The Alfa Whisperer, I call him.
I guess the good thing about a '95 car is low depreciation. If it weren’t for that, I would have been better off with a new Ferrari. 
But, on topic… are there cars out there that beat the Prius’ mileage, or does it still reign supreme?
Not for long. Toyota’s Hybrid Synergy Drive is not the end-all-be-all of alternative propulsion. There are other manufacturers making vehicles that look better, go better, handle better, and stop better. And are loads more comfortable to boot. If GM ever comes out alive from it’s dire state of affairs, you can bet they’ll be putting significant effort into stretching their dollar on Delta II / E-Flex / Voltec platform upon which the Chevrolet Volt will be based, and will probably build it in multiple guises for different brands in different markets. It could potentially turn the tables significantly in their favor in the fuel economy wars … a car that could (if not driven beyond 40 miles at a time between charges) produce economy figures well into the triple-digit range because it would not use a drop of fuel until the battery runs down. Granted, it will have a steeper cost of entry (likely to be in the high 30’s unless tax credits can bring it down to low 30’s or high 20’s). In the meantime, there are competitors that are cheaper to own and better value for the money, and which use same principles of internal combustion we’ve had all along without any hybrid assistance.
You may make jabs at your VW being boring, but Volkswagen is at present a recognized leader in bringing clean turbodiesel to market in Europe. Trouble is, they aren’t bringing them here. Not yet, at least. The only model on sale here at present is the Jetta TDI. They are not the only manufacturer building turbodiesel models for the European market, but they are making some of the cheapest, most recognized, and most purchased ones. A variety of Volkswagens (and Audis) will be made available in coming years with TDI engine options. A new Golf TDI is also on the way. I could go into enormous detail on this, but it might just be easier to give tdi.vw.com a look see. They are turning in numbers not far off from the the Prius in a heavier car and using plain old internal combustion. It should also be noted that Volkswagen is hard at work on equipping TDI drivetrains with a hybrid system not dissimilar to the offerings by Honda and Toyota. A turbodiesel hybrid could easily return figures of 70-80mpg and are probably not far off from production. When that happens, VW will really have Toyota & Honda by the balls because neither one of them has any investment in turbodiesel technology. I think VW has the potential to rocket way past them in the fuel economy wars in the not too distant future.
Ford does have hybrid offerings in the Fusion and Milan hybrids which return 41 mpg city. They aren’t really my thing, but I’d still take one over a Toyota without reservation. Perhaps it’s because I still have a pulse. 
So what would you recommend for someone concerned about price, emissions, and mileage?
If that’s really your only criteria, then the Prius and Insight are really your only two options.
I’m impressed with your record keeping. I’ll do no such thing, so I have to rely on the car. Our Prius sits at about a 45.5 average most of the time. Our driving is pretty much all recreational highway driving, so it is exactly as advertised.
Coldfire: I’m pretty sure the Honda Insight gets better mileage than the Prius; but it’s a two-seater.
I saw an article on the 2010 Prius the other day. It said the 2010 has a larger engine than earlier models, which means it’s not working as hard at freeway speeds and actually gets better mileage.
My previous daily-driver (which I still have – snow, y’know) is a '99 Jeep Cherokee. I can’t tell you how much more comfortable the Prius is to drive. The Prius has more legroom, more space between the driver and the steering wheel, a better ride, rear doors that are easier to get in and out of, and back seats adults can actually sit in with enough legroom to be comfortable. Plus, while not as high as the Jeep’s cargo area (seats up or down) the Prius’s cargo area has approximately the same floor area as the Jeep’s.
The Prius handles better than the Jeep (though not as good as the MGB or my previous car), and stops better too.
Driver8: Well, I don’t have anything better to do. 
Actually, after owning it for a month I was curious about how accurate the mileage display on the Navigation system was. So I made a spreadsheet with the date, odometer (trip meter) miles driven, gallons loaded, indicated MPG on the Nav unit, calculated MPG (trip meter miles/gallons), the percentage difference between the calculated MPG and the indicated MPG, average MPG since I started keeping track, and the average difference between the indicated and calculated MPG. I don’t drive much on weekends or telecommuting days, and the three commuting days are nearly all freeway with rather a lot of stop-and-go for about 20% of the trip.
Wrong on both counts. Firstly, you’re referring to the old Insight. Also goes by “The car that nobody bought.” I’m referring to the new 2010 model. It does not have two seats. Secondly, it is does not get better mileage than the Prius.
When I said there are other manufacturers making vehicles that look nicer, go faster, handle better, and brake shorter, I meant hybrid and turbodiesel passenger cars, not SUVs. Comparing the handling of a compact (even a softly-sprung Prius) to an SUV or truck is apples and oranges. The Prius and Insight are not going to win any handling or ride comfort contests against most of the hybrid/turbodiesel competition. But that is why they are the cheapest offerings available …
I should also clarify that to the Prius’ credit, it is, as you say, a much more ergonomic and accommodating car, but that isn’t saying much as you are comparing to a Jeep Cherokee, which has never been anything close to a model of efficiency and ergonomics. You’re at two totally opposite ends of two different spectra … Toyota vehicles may not be terribly engaging, but like most modern cars, there is some thought put into their passenger ergonomics and packaging. Nobody will ever accuse the Jeep brand of spending more than a minute on that sort of thing.
I stand corrected on the Honda. I’ve only seen the older ones.
My point in comparing the Prius to the Jeep is that while there are other cars that are superior to the Prius with regard to the things you list, not everyone is going to be going from a similar type of car to one (or one of the others). So compared to what I was driving before, it’s better.
FWIW I average 20 mpg in the Jeep, and I’ve seen as high as an average of 25 mpg when I’ve driven it very carefully. Again, this is on the freeway and the engine is just loafing.
Heh, you bring to mind one particular segment from BBC’s Top Gear which, to me, has always served as a terrific reminder that it’s not what you drive, but how you drive it that most impacts your fuel economy. Granted, that notion would cease to hold up when comparing a compact hybrid to a large truck or SUV, but again, two very opposite extremes.
I know Jeremy Clarkson is bonkers and exaggerates everything but I find him hysterical and I still crack a smile when watching this segment! Toyota Prius vs. BMW M3
(The opening 30 seconds are from a previous segment about comparing the fuel efficiency of several sports cars to determine which one was the most frugal)
More required Clarkson-meets-the-Prius viewing:
First generation Prius review
Second generation Prius review
Well, crap – speaking of the Prius.
The gardeners were over today. I used the hatch of the Prius as a table to write them their check. That’s when I noticed the skinny window below the spoiler was broken. I don’t know if they did it, but there’s nothing to mow behind the car so it’s plausible they didn’t. I also saw the next-door neighbour (or someone working next door, anyway) riding a riding mower in the street and turning around over a patch of grass with gravel on the verge across the street. And my Canadian neighbours are in town for the weekend, and he was mowing. So there’s no telling who did it.
Diesel cars will easily beat that MPG. My mother’s VW Polo Bluemotion does over 80 MPG.
That’s what I’m trying to tell them. Richard Hammod drove that same BlueMotion in an episode of Top Gear during an “economy race” and was in the 70mpg range. Trouble was, it’s got a fairly small gas tank, so he couldn’t finish the entire legth of the race. I’ve also read of a BlueMotion Passat prototype that could achieve 45mpg. That is an impressive figure for the Passat, which is no lightweight at 3,300lb (a good 300lb heavier than the new Prius). The only reason the Prius is tipping the scales at 3,000lb in the first place is because it’s saddled with nickel metal hydride battery packs and electric motors, not because it’s sturdily built from higher quality materials. Prius owners though, y’know, what can you do … like the South Park episode, they’re too busy enjoying the smell of their own farts (maybe the car exhaust, also) to realize that turbodiesels are cheaper overall and get better mileage. About the only real advantage an electric hybrid drivetrain has is the fact that it has lower emissions by design because the engine is not running at low speeds or at idle. If the same hybrid drivetrain technology were to be applied to turbodiesels, not only would emissions be at the same level as a Prius or better, but the economy figures could potentially reach triple digits on a small car like the Polo or Golf.
Of course, we still can’t get BlueMotion models in America. Not yet, at least. I know VW is keen on introducing them here, but I think they want to produce them domestically at the new plant in Tennessee that they’re investing $1 billion into, which will open in 2011. They will be producing a brand new (and as-yet-unnamed) midsize sedan model for the American market which is intended to go toe-to-toe with the Accord and Camry. No word on whether this will replace or supplement the Passat, but I’m going to make an educated guess that it will be available in TDI and/or BlueMotion trim, as will other TDI models coming from that new plant.
Throwing out a datapoint: I have a '09 Camry hybrid. It’s got the same system as the Prius, only with a large gasoline engine and the car itself is heavier. I get, on average, 36 mpg.
However, by the actually existing car which one can actually go out an purchase metric, the Prius and Insight do have some advantages…