In a few days my 2004 Prius will be 5 years old. I log every tank data so here are my stats: miles: 58,463 (11,693 miles/yr avg) gas used: 1088.8 gallons (18.2 gallons/month) lifetime mpg: 53.7 mpg savings vs. 25mpg car: $3,049 total maint cost: $880.63 ($176.22/yr) See all the data at Prius Gas Mileage See the maint log at Prius Maintenance See the charts at Paul's Prius Home Lowest mileage points were road trips with passengers/luggage. The drop a couple of years ago was due to 10% ethenol being added the same week I got new tires.
Looks like a bit of consistency between your five years and mine. The weather-related mileage and the hit taken with new tires. Nice chart. Having also charted every tank, I know that sometimes you might wonder just why you keep doing it but it's for the end results, for charts like this that everyone can learn from. Thanks. Tell your Prius "happy birthday" for me.
The new tires went on the same week as the addition of the 10% ethenol so that was a double hit. The tires have finally broken in but the ethenol is still hurting my mileage. I've got mileage data for my previous 2 cars back to about 1984 (Isuzu Impulse then a Saturn wagon). I think some of it is carved into stone tablets.
Keep up the data! I tried the same thing but with the wife driving it most of the time, she never remembered to write anything down or give me the receipts. We're headed on a 6000 mile trip this coming week and I plan on keeping all the stats and posting them. We'll be running a gps, computer and XM radio on the car the entire trip... Should be fun!