34 mpg

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I use my AC all summer (17c - 19c never more than blower position 2), but manual settings only - I never switch it to Auto, as that uses more fuel, I believe.

It seems you do a lot of short journeys. The Prius is most economical when the engine is warmed up and you're doing longer journeys.
Having said that, swot up on hypermiling techniques and that might help you elevate your MPG.

Do you actually have LRR tyres fitted? Y'know, Low Rolling Resistance tyres that'll help save fuel?

For repeated short journeys where the engine never fully warms up you'll end up with less mpg.

Climate; is that 60f....?

Could be your tyres.


iPhone ?

 

Those tires have about 5% bigger circumference. So that would be the difference between 34 and 36MPG.

K&N filter won’t really help you. Modifications on Prius don’t really help much with fuel economy.

When you drive how hard do you brake to stop? Big difference between the Prius and normal car is regenerative braking. If you brake hard Prius uses normal brakes loosing energy.
When you deliver to customers do you turn the Prius of at their end? Turning the Prius on and off all the time wastes energy.

 

Sprockit - All the short trips really hurt the mileage. Our mpg often averages low to mid thirties during the winter when the car is only seeing short jumps of 1-5 miles at a time all week long and that is not even factoring in the colder weather. Early in a tank I often see 29 mpg on the screen.

With your car being the same year and the a Touring like mine I'm assuming you have the Smart Key. When it's safe to do so try to leave the car turned on when you are delivering those pizzas. With the Smart Key you always have the panic button on you , the key isn't in the car and both Data Daedalus and valde3 are correct. The gas engine automatically starts every time you hit the start button whether the car is warmed up or not. That alone will really kill your gas mileage.

As long as the car still gets in the 40s on the highway there's probably nothing wrong with the car but I do have one other suggestion if it doesn't. Get the brakes checked to make sure the emergency brake is releasing all the way and check that one of the other brakes isn't "dragging".

 

If you are going to continue to use the car primarily as a pizza delivery vehicle you're going to beat up any vehicle you use. Make sure whatever you drive is a solid performer and dependable.

As a comparison we bought a 2007 Toyota Yaris in 2015 for my wife to commute to the train station for work. 8 miles each way with low speed limits. A lot of signals and stop signs. She has averaged 32 mpg with that car. We averaged 33 mpg with the 2003 Echo we had before that but the mileage included a little more 65 mph driving on the highway.

Personally I wouldn't switch unless I could sell the Prius for more than what I could replace it with. To take a loss will never be made up by the few Euros you might save with a few mpg of improvement. Also, I don't think it's worth the risk of buying a different used vehicle and possibly getting someone else's problems in an attempt to save what amounts to only a minute quantity of fuel per month. I would continue to drive the Prius (a nicer car) and set aside a savings account for that inevitable day when a replacement is needed.

 

You can lock the Prius running. But then you do need the mechanical key to get back in. So this probably isn’t practical.

TDI is only good for longer highway drives (some would say that it’s not good for those either).

 

probably just a civic or something simple like that.

 

Sprockit - To give you some perspective, we just went and filled the car after 177 miles because we're going to be driving a couple of hundred miles tomorrow and I don't want to mess with it then. This 177 miles consisted of no drive longer than 4.8 miles in cool (by southern California standards) temperatures and rain. End result was only 33.58 mpg but I'm not worried. We'll get mid 40s to 50 mpg tomorrow on the freeway as we run to L.A., Orange County and back.

Allowing the car to warm up and longer trips make a huge difference.

 

Short COLD trips hurt MPG. But if you are doing many of these trips back-to-back, with the engine staying relatively warm in between, these short runs shouldn't hurt nearly as much as short commutes with 8+ hours of cooling between trips.

CHECK THE OIL LEVEL!!! Nevermind MPG, this is for protecting the engine. Neglected oil and undetected low levels have caused way too much unnecessary damage. Some models (e.g. my first Prius, a 2010, and now my 2014 Subaru) are notorious for developing oil consumption problems. Drivers who never check oil themselves end up learning this the hard way, after permanent damage crops up.

12V batteries on the verge of failure are a common contributor to low MPG, especially in winter, especially in the few months before they give up the ghost. Check it, use the procedure listed in one of the above linked threads. Your Gen2 has a built-in voltmeter accessible from the dash menus. Other generations lack this built-in meter.

This tall tire hurts displayed MPG in multiple ways, some of it real, some of it just illusory.

That tire is about 5% taller than OEM, throwing off both the speedometer and odometer. You are going 5% faster than the speedo says, which makes a difference if you are looking at Bob Wilson's MPG-vs-speed chard. This hit is real.

Your odometer is also under-reading. When it says you have driven 40 miles, you have really gone 42 miles. This hit to MPG is illusory, because it is calculated from a 'fake mileage'. Adjust your displayed (or computed from odometer) MPG numbers up by 5%.

If the tires are not LRR, you may lose several percent compared to better tires, but this is almost never a reason to discard otherwise good tires, as the saved fuel will not cover the cost of throwing away good rubber. Also, new tires lose an additional several percent temporarily until they are broken in.

In winter, both AUTO and this high temperature will have an MPG impact, especially in your non-highway delivery circumstances. But if you need the heat (or A/C in summer), you need it, so that is just a cost of using the car.

 

As expected, the mileage went way up yesterday. Spending almost two hours in rush hour traffic to L.A., an hour on the freeway coming back and the other running around the MFD is showing 147 miles and 50.1 mpg. Based on past history that means the car probably is between 47.5 and 48.5 mpg if I were to fill it up and do the calculation.

How the car is driven makes all the difference in the world.