i am having this conspiracy theory: i suspect that the dashboard MPG is displaying the imperial MPG as UK mpg as supposed to US mpg.
Conspiracy theory! OK, I needed to know, so I went and read the meter using both display settings.
My car is US/California model, so you might need another Canadian car to prove theory.
When I started measuring I was at 45.1 MPG then 19.2 km/l then engine kicked on and it 5.2l/100km but then since engine kicked on, MPG fell to 45.0MPG, so accuracy might be off a little.
Anyway, I went here for calculator sites.google.com/site/scmrak/fuel-economy-calculators-and-converters
5.2 l/100km = 45.23 MPG(US) which is off by only 0.13 and 45.1(US) =5.215 l/100km which rounds out correctly, so I would guess the computer is calculating in MPG, and then converting to metric. It might also be calculating in Imperial and converting to US or vice versa, which could throw off the accuracy.
But converting the metric to imperial it is clear my computer is not showing Imperial MPG, 5.2l/100km = 54.2769 MPG (imperial)
If you read the CleanMPG and PriusChat forums' tips on hypermiling you might understand how people can get fantastic MPG. Some of the tips in this thread are technically WRONG. Best MPG is not at 55 or 65MPH but much slower. Accelerating quickly will rarely give you better MPG. The hypermiling champions accelerate very slowly and go very slowly. People who get better than 50MPG either piss the people off waiting for them or they drive in ideal places. But some tips like accelerating quickly do have some merit, because technically our engine is most efficient at about 2000 RPM and about 80% load. So accelerating quickly but not at wide open throttle can yield good gas mileage, so the posters that recommend it are not completely wrong, but it is rarely the best gas mileage. It is tough to beat slow driving for maximum MPG. Hypermiling experts will drive slowly, use a scan gauge to keep ignition advance close to 13 or 14 degrees and use pulse and glide (accelerate and coast) technique. But even pulse and glide is not ideal all the time. There have been studies where cruise control beats out pulse and glide. I have practiced some of these techniques and can get the MPG up over 50MPG for many miles, but NOT for a full tank!!! Commuting, short trips, hills, and traffic, bring my MPG way down. Like the original poster, I am in San Diego and it is tough to get good MPGs here. I bought my CT only about a month ago, so still learning. Whether driving slow or fast, the car is a blast! Check out the PriusChat forum for great tips. One thing I learned from there is that our Michelin Primacy tires are about the sportiest Low Rolling Resistance tires and they don't give as good of gas mileage as Michelin Energy and a few others, so if you want to make a compromise, you can get better MPG by switching to even lower rolling resistance tires than the Primacy.