Technology

That's crazy. Gas is less than half that in the US (<$3/gal in my area, just over $3/gal national average). If my gas was $7.50/gal, I'd definitely be driving electric.

My overall miles per gallon was 85mpg including electricity.

The 53mpg is within other tests (ex: consumer reports), and is within expectations.

Why does your car calculate your petrol efficiency but not your electrical efficiency?

On the contrary. I don't trust Toyotas EV efficiency figure of 3.2mi/kwh because I'm measuring 2.2mi/kwh from the wall.

Are YOU measuring the electrical output from the wall correctly? The cars battery has a figure but it's after the efficiency losses in the cable, heater and other such figures. My calculation includes all the losses except voltage sag in wires (1.5% estimate)

L2 charger at work returned 3.4mi/kwhr !!!!!

L2 charging at 50F (and below) is clearly way more efficient than L1 charging.

With this, I can safely say that L1 chargers should be avoided if possible.

Of course! I plan to keep this car for around a decade, so there's plenty of opportunity next year to experiment again.

Between the heater during charge + the heater during driving (!!!), we are getting hit twice by the cold weather efficiency demons.

Today was 50F (10C) and I'm estimating closer to 3mi/kw-hr.

Or in other words, warmer weather is close to +25% more range and efficiency compared to last week's cold weather test.

Note that this number is very preliminary (ie: reliant upon Toyota's battery measurements) and I'm currently recharging my car with the Kill-a-watt to verify my initial estimates. I've also got a work meeting tomorrow morning, but I'll try to write down the results of today's warmer weather test and report back to you.

Alternatively, if I forget to write down the Kill-a-watt results tomorrow morning, I'll just repeat the test again on Wednesday or something. It should be warm weather all this week.

2.87mi/kwhr is the final number for 50F test.

That's +38% range. Or conversely, a 28% drop during freezing conditions. Or 72% efficiency near freezing compared to 50F.

Measured from Kill a Watt and therefore still a L1 charger that may have other inefficiencies.

Huge differences between 50F and 30F. Very curious indeed

The manual of mine specifically points this out and says that if you go three months without burning any fuel the engine will start being used until about a third of a tank is consumed.

Yes but there is an easy solution. Just fill up with 2 gallons, rather than 10 gallons.

Now you have the 100mi backup gasoline (why you bought a PHEV, right?), but still do EV every day. Every few months hit the HV button and burn off that fuel and fill up another 2 gallons.

That being said: Prius Prime dual mode has 0-60 time of 6.6 seconds. When both engines are on your acceleration is amazing, on both low end 0-30 EV) and high end (ICE engine covers 30-70mph).

So you want to be in auto mode (aka: use both engines mode) anyway for optimal driving experience.

And now that I know that gasoline is cheaper in the winter anyway, maybe I push that 'use both engine' button more....

If you ever need the 500mi gas tank for a long trip, just spend 5 minutes at a gas station. It's not like our gas tanks are locked behind 20+ minute chargers or whatever.

most hybrids run the engine for a few minutes a month anyway, as a precaution. keeps it lubricated and sloshes the fuel around to prevent it from layering.

also i don't know how common this is but my car pressurises its tank to prevent offgassing, which apparently keeps the fuel good longer.

Not to mention, for a naturally aspirated IC engine, you actually make more power in cold weather due to it being more thermodynamically efficient with a colder intake. (This is the reason why an intercooler increases the power output of a tuner car.)

How is that rate possible? My UK (Octopus) electricity rate is 23.44p/kWh. The energy price cap is 24.5p/kWh. There cannot be anyone out there offering a price of 6p/kWh - I suspect you are looking at your gas price (where 6p/kWh would be about right)

Interesting. The internet suggests 22p/kwhr is the UK average ($0.27/kwhr in US dollar)

I do have a time of use program that I could take advantage of to drop my night time / off peak prices. But my on-peak prices go up so much that even with the EV I'm not saving any money.

I'm only going to drop from like 17c to 12c if I switch to the EV time of use program, or a change of like $1.70/night worth of charging to $1.20/night (10kwhr per typical day of travel)

Do UK citizens pay generation + transmission + taxes like we do in the USA?

8p/kwhr (10c/kwhr) is very close to the time of use / night time charge generation costs of my area. However, there are still local tax, surcharges, and transmission I have to pay for that would take that up to 17c when it's all accounted for.

Thank you for converting it. Great to see how it would compare around the world