Significant Drop in Gas Mileage

I was wondering if anyone else has had a similar experience and if they could provide some guidance?

We noticed a significant drop in gas mileage in our 2012 Prius V after driving the vehicle for about a year and a half. We purchased the Prius V brand new from the dealership. The car started out at 4.8 L/ 100 Km (we live in Canada so everything is L/100 Km.) The car was sold with the specifications of 4.5L/100 km so we thought 4.8L/100 km was pretty good. After about a year and a half the gas mileage oddly started to rise. Nothing changed in our driving habits. Our weather has been seasonally consistent, we have not had any unusual winds changes, and change our tires regularly with the same brand. We are at a loss as to why our Prius V keeps getting worse gas mileage. It slowly went to 5.8 L/100 Km and currently sits at 6.3 L/100 Km. Our Toyota service center tested the vehicle and said everything is fine. Does anyone have any suggestions as to what we can do get our Prius V gas mileage back to 4.8 L/100 km?

 

Some good points. I was concerned as well and did a little looking into the same questions a few years back. Canada gas producer do put ethanol in their gas and have been since the 1980. There has not been a change in in ethanol mix in the last 20 years so I ruled this concern out as a effect on our Prius V gas mileage decline. We get our gas at the same gas station as we collect aeroplan points. It is a brand name gas station so I would imagine they use their own gas refineries and it would be consistently produced. We have always used supreme unleaded Octane 91 so am pretty sure it's not the gas type. We regularly change our tires and have used the same tires the car originally came with. I am a worrier and have my husband check the tire pressure on a regularly basis. He rarely has to top up the air. We appreciate your reply. Still trying to figure out the gas milage drop. Hopefully someone might have a good idea?

 

Some good feed back. The breaks are checked yearly at our Toyota dealership and maintained as required. We ruled out the breaks having an effect on the gas mileage. The Prius V has been driven consistently. After the spike in gas usage after 1.5 years of driving our new Prius V we have seen consistency for the last 4 winter and the last 4 summer of 6.3 L/100Km in the winter and 6.1 L /100 Km in the summer. I used the L/100 km rating given in the car dashboard display. My husband tracked it manually for two years. We did not find any difference from the car dashboard display and the manual table my husband created. Since the manual table (distance driven vs gas put into the gas tank) and the gas mileage display were the same we just use the gas mileage display on the dash board now. Is this something rare? Has anyone else with a 2012 Prius V had a similar big spike in gas usage? Would like to hear how you fixed the issue?

 

We could change to regular gas but I wonder if that would add variability to the issue at hand? We had a spike in gas use from 4.5 L/ 100 km to 6.3 L/100 km always using the same gas. Why would the gas consumption after a year and a half all of a sudden spike up? The gas we used was consistent. I wonder if we can rule out gas having a effect on gas consumption if it stayed the same since we purchased the car brand new?

 

We have always used the same tires over the years. We purchased all our the same tires from our Toyota dealership. No change to our tires. I think we can rule out tires or tire pressure having a effect on our poor gas mileage over the years 4.5 L/100 km spike to 6.3 L/100 Km. My husband told me tire pressure could be a big contributor in spike in gas usage on our Prius V. That is why I had him check and log the tire pressure on a regular basis.

 

My husband drives the car 52 Km to work. He starts early at 5:30 am. He drives mostly highway and at a consistent 100 - 110 Km/hour as rush hour has not started. He drives home at 2:45 am and does 90 to 100 Km/Hour as he is ahead of traffic. The 52 Km home is also mostly highway. Would that have an effect on the change in gas mileage from 4.5 L/100 Km to 6.3 L/100km?

 

What do you mean sustained high speeds are tough on mpg, very linear relationship? My husband has been driving the same route at much the same speed (100 Km/hour approximately 60 mile/hour) since we owned the car. What are you suggesting will help get our mileage back down to 4.5 L/100 km from where it is now 6.3 L/100Km?