Hi there, having the same spec car as the original poster , and being a hypermiler fan, I can say for definate - sorry but you cheated.
When you press the 'clear' button on that computer that reads 99.9mpg and hold it in for 5 seconds, it clears the mpg average info and reads blank untill youve done about 1 mile of driving, and then it gives you the average for that mile. Its not difficult to press that button while coating down a long hill !!!! I have done it lots of times for the fun of it to show other people shortly after pulling over - wow how do you get 99.9mpg, or drive a little further untill it comes down to 95mpg, then 80mpg .... 68mpg so forth...... you can trick anyone to belive thats your average, when in actual fact its the average of when you 'cleared' it, to when you pull over and take a photo!!!!.
I hope you all get my drift? That 99.9mpg could mean 450mpg !! but it only goes to 99.9mpg and it only does this when coasting, im sure the original poster did not spend his whole journey coasting therefore thats very misleading.
he said he got 51mpg? Hes just plucked a number out of thin air, or perhaps thats when the computer went from 99.9mpg downwards and he stopped the car, if he'd kept driving it would have gone down further probably to 32mpg or there abouts, unless hes a really super hyprmiler, the average on these are 36-40mpg when you try all the time tank to tank. It takes a big effort, they are big and heavy turbo'd cars of a 21 year old design.
The original poster got carried away, and misled us. tank to tank is the only way to get real figures, we can all choose a convenient trip to show of mpg figures but that not real average mpg figures.
On a side note, I once managed 50.1mpg in said car -saab 900 se turbo- and that was after driving 160 miles at about 55mph. as soon as I went back to regular roads it dropped and dropped and dropped
These are bad cars for hypermilers, no harm in trying.... but misleading should not be aloud on here. all the other members work hard to get good mpg figures and one clown comes along and shrugs off electric vehicles, because he knows a 'trick' on the mpg computer is not going to help any of us.
Anyway, sorry for my first post to be a negative one, but real efforts should not be overshadowed by fake or misleading efforts. hope you all agree