What is your trip mpg on short drives? Gen 4

On my old Gen 1 Prius I got terrible gas mileage around town because no matter where I went I started with 5 minutes of the engine idling at red lights, stop signs and school crossings. The engine always ran until it warmed up enough. By that time I was at my destination where it would sit for an our or so and cool back down.

Fast forward 20 years, and my Prius Prime is just made for my situation. All my around town errands are run on electricity. I never have a 2,3 or even 10 mile drive where the engine fires up.

 

It's about averages. Short drives can be relatively meaningless. The shorter the trip, the worse.

If I drive to the shop (1½km), sometimes it'll be 10l/100km there, and ZERO back. Other times, the reverse. To Mum's house, 7km can vary between 3.5l/100km and 5.6l/100km.

But on a run to Church, it'll be about 3.9 - 4.2 every time, both ways.

 

My very crude rule of thumb is that a cold engine warmup cycle costs about the same of fuel as driving 2 miles on a fully warmed up engine. I started this rule on a non-hybrid vehicle, and still use in on my Prius.

By this rule, your 8 mile drive from a cold engine is fuel equivalent to 10 miles from warm. So your 38 mpg on commutes should correspond to 47-48 mpg on much longer trips.

This rule is coarse, and breaks down more on trips short enough to not fully warm the engine.

 

Yes - and it depends on whether you're starting with 2 bars of hybrid or 8.

 

Also starting from cold has a huge impact... the lubricants are more viscous, the cabin needs to be heated or cooled to the set temperature, the engine will run until it's warmed up. All of this energy comes from originally from the fuel.

For what it's worth, I do similar sized journeys every day with my kids, taking them the nursery and school, then picking them up again. I'm usually starting from cold each journey. I'm averaging around 55MPG according to the computer. 50 in colder months, 60 in warmer months. I can easily push that 10MPG higher if I driver more economically, but rush hour driving requires some "spirited" acceleration when pulling out at into tiny gaps at junctions / roundabouts.

Also bear in mind a UK gallon is 1.2x a US gallon, but I'm not convinced that's actually accounted for in the software. If it is, those figures would be closer to 42US-MPG and 50US-MPG respectively.

 

Sounds about right for short trips. The Gen 4 has a "diary" type of display that shows accumulated MPG on a daily basis. This value updates in real time so you can observe the lower MPGs upon starting out and watch it grow as the trip progresses.

 

40s, but also dependent on day temps that day. the hotter the day, the better my chances are at high 40 mpg short drives...

 

That's part of why my next new car will be a Prime

 

I've noticed similar on my (relatively) few short trips. When I take my son to/from his job my round trip runs 12-14 miles.
Starting cold & running 25-30 mph in the neighborhood for the first mile and I'm usually under 30 mpg but the final number upon returning is low 50s to low 60s, depending on which route I choose. The warmup time really bites hard.

 

The warmup time is really tough. In the summer when it’s 70-80 degrees, I’ll get to 50-ish mpg within a few miles. Now in the fall, with temps in the 50s (F), it takes much longer to get there.

 

Hello Higgins909.....I am fortunate to park my car in a heated garage. On a short trip as you state, I average aprox 82 mpg.

 

I’m a fairly new owner and new to hybrids, but here goes: our Gen4 2022 will get about 24 mpg on the chilly mornings for a short 1to 2 mile run to the store. Once it is heated up (ie: headed back home from that same run), it gets about 60 mpg. If it is foggy or I need to run the lights more, it will drop a mile or two.
For the ten mile run to the next town (actually where the dealership is) for a cold start, the run over gets ~50, the return trip is ~65, (running the speed limit of 65).
We have about 550 miles on it and our average since new (including the test drive and sitting in the driveway in February learning how everything works) is 48.1 and increasing each time we take it out.
These averages are based on driving it to achieve the best mpg we can as we learn more about the car.

 

I have a 2018 Prius and I get 52 for the last couple of years since I bought it ( new ). Last winter it dipped to 47 but now it's up to 56, which happened just after my first experience with a check engine light. I'm going in Monday to get the engine light diagnosed. ( I'm at 100k ) but I don't know if the light has anything to do with the better mileage, that doesn't make sense.

 

If you are going by the mpg indicator, it's misleading. If you reset Trip mileage A, for example, it won't register your true mileage until you drive it a while, maybe 50+ or so miles before it indicates your true mileage. If it says 22mpg, for the first few miles, as I understand it, that's not what you are really getting. It might even go up to 60 something, but drive it until it settles, and that is what your mileage is. IN fact, what I do is, when I fill the tank, I look to see how many miles are remaining. If I have a 10 gallon tank, and I fill it up and it says I have 520 miles left, I figure my car is telling my I'm to expect 52 mpg. No matter what the mpg indicator says on the dashboard, I always have around 520 miles remaining or so after fill up. However, I live in SoCal so I don't know about cold weather and how it affects the mpg.

The best way, however, to figure mileage is just to fill up the tank, keep track of the miles and gallons, and when you fill it up again, divide miles by gallons and you'll get your mileage. (I think that is how you do it, I forget ). I've done this before, but since it pretty much agrees with the 'miles remaining' calculation, I just go by that method.

 

Spring is here, MPG goes back up with the warmer weather, drier roads, and summer fuel blends. Then it may drop a bit as summer air conditioning season arrives.

Why mileage gets worse in winter | PriusChat

I very strongly disagree with your Trip meter MPG comments. Your claim would be startling to nearly all long-timers here.

Those low numbers over short distance after resetting a Trip meter are not misleading, they are very real, and betray the fuel penalties of engine warmup from cold starts and short trips.

High numbers from a cold start happen on early downhills, where it needs little or no fuel to glide down. The figures go back to 'normal' once more flat miles are added in. Immediate hill climbing makes the early numbers even lower.

That generally works when weather, driving conditions, and speed patterns are consistent. But throw in changing and foul and windy weather, significantly different speed limits, differing plains vs mountainous routes, differing elevations (high plains vs sea level), and different road surfaces, then your guideline begins falling apart.

Numerous new owners draw misleading inferences from the Distance To Empty guess-o-meter. It means much less than many of them think. The car is quite unable to forecast how future driving conditions will be different than recent past conditions, so this display sometimes diverges very significantly from reality.

 

No problem, I will defer to the wisdom of the experienced. But, after a few miles, say 50 or whatever, the law of averages does kick in, does it not?

 

Apparently I wasn’t clear in my post. Those low mpg numbers aren’t results when resetting trip a or b, they are actual trip figures. I realize that many feel that the displayed mpg numbers are not 100% accurate. However, neither are the numbers one gets when you divide the number of miles by the number of gallons you pump into the vehicle UNLESS you are willing to do the following EVERY TIME you fill up:
1. Measure the ambient temperature
2. Measure the temperature of the fuel you are adding
3. Measure the temperature of the fuel in the tank
4. Measure the temperature of the air volume in the tank
5. Apply all of the conversion factors necessary to convert all of the preceding data points to a common reference
6. Then apply the simple division
Now, you will approach a more accurate figure IF each and every time you fill up you use the same pump (assuming the electrical system voltage at the station remains constant), and you enter that data in a spreadsheet. However, it won’t be 100% accurate. But using those figures it will give you an idea of your approximate mpg.
OR you could simply use the onboard data points and come up with an approximate mpg, and enjoy doing other more activities with your time.

 

Is there an app for this? If not, there should be. I'd like to know what my mileage actually is.

 

Why not trust the readouts of the car? My 2022 has one for miles on the odometer, one for trip A & B, and one for the current trip, plus historical data back over several time periods. We have left the Odometer one and trip B alone since we bought the car in February and they agree within 1/10 of a gallon.