Long SF-VA trip with 87xx ft climb I-80

Flashlight, water and snacks to survive a day or two if stuck in a remote area, blanket for camping in a stranded car, footwear and outerwear for cold rainy weather in case of needing to walk for help, cell phone with service on a major provider network with better deep rural coverage (Verizon or ATT or one of their many MVNOs), etc. ...

 

If I were planning a cross-country trip, I would buy a compact spare and carry it vertically behind the front passenger seat. I got mine from eBay that came from a Lexus CT200H. Other Toyota models had them, too. I would then install it on the car and drive around the block just to see that I had and could use the tire tools that came with the car. If you search previous posts on "flat tire" or "spare tire" you can find the correct specifications for the spare.

 

I could list all of the items you’d find in my car, but @fuzzy1 has kindly mentioned the important basics. It’s also convenient to have a pair of leather work gloves, a reflective vest to wear if you must get out of the car near moving traffic, and a knife/multi-tool (Gerber, Leatherman, or similar).

Specifically for Prius cars, I’d suggest a 10 mm wrench, to disconnect the negative (–) terminal of the auxiliary (12-volt) battery under the hood, which resets the car’s computers. This isn’t an official procedure, but it’s sometimes enough to get a stalled car moving again, at least temporarily.

@Washingtonian makes a good point about a spare tire. I’d definitely want one for driving on back roads, but along a major highway, in a new car with ToyotaCare roadside assistance coverage for towing, it may not be quite as valuable. I’d choose to have the car towed, even at my own expense, before I’d drive more than a very short distance on a limited-access highway at 50 MPH, the speed limit with a compact spare installed.

 

Before replying, I should have glanced in my car to remind of more of my stuff. Yes, I also have everything listed in your first paragraph. While I lack a wrench specific to the battery, I do have an adjustable wrench, and also a socket handle for the hard-to-remove-by-hand valve stem caps on my original wheels, where the covers don't leave enough room for much finger grip. (These caps may be specific to the dealership's bogus nitrogen upgrade.) My other seasonal wheel set has no covers so the valve caps are easily removed with fingers alone.

Also in my car are a medium sized first aid kit (larger than my lightweight hiking kit), remnant (not full) rolls of duct and electrical tape, and a window washing squeegee (dating from before the collapse of window-smearing bug populations). Old paper maps of all relevant states (collect whatever you lack from rest stops or visitor information centers as you pass through). Matches or lighter. Spork (plastic single-use tableware saved from fast food joints work just as well). P-38 can opener. A few spare plastic grocery bags, the kind many cities are banning. Plastic tarp (use as cover, ground sheet, even emergency wind breaker or rain poncho).

Lower tier items, much less essential, derived from the old days when shovel and axe and bucket were required when visiting National Forests during fire season: small folding shovel, hatchet or folding saw, and collapsible bucket. These are far more relevant to folks camping off-pavement in the woods than to folks staying on Interstates or major highways.

 

I must say I did this (buy a spare) and carried it with me on my X Country road trip in my 2013 PiP. I went many miles between any town out west and although I didn't need it, I felt better knowing I had it.

I plan a similar trip (east coast to Calif and back) next spring in my Prime, which will still be covered under the "Toyota Care" (free roadside assistance). Even though I will have that roadside service free, I still plan to bring the spare just in case I get stuck 50 miles from help.

The considerations are these; it will take up space which is limited and you want to have it secured in case of collision, so it does not become a missile.

 

One other thing. Bring the charging cable so you can charge at the motels you stay in.

 

If you have snow tires on separate wheels, you could consider carrying one as a spare if you have room, instead of buying a compact spare.

 

Also, if not using existing EV charging points, possibly consider a good heavy duty extension cord to be able to reach more standard electric outlets at common lodgings. And since the Owner's Manual discourages extension cords, be sure you know how to turn down the charging rate to just 8 amps. This will cover some of the sins of extensions cords, or at least the shorter ones.

 

Nobody has yet said "a gas can", so I will

 

That is an item I intentionally don't take. Most people's cars don't suffer sudden unexpected un-warned empty fuel tanks.

Though for the people who do tend to get such cars, well, they likely know who they are.

 

I don't have a Prime yet, but doesn't this defeat the very reason for a plug-in car? Plugging in to the grid is meant to displace dinosaur fuel. But charge mode defeats this by burning dinosaur fuel to recharge, when it is really more efficient to skip that step of laundering energy from engine through the electric inverters into the battery and back out again.

Charge mode is fine for preparing to quietly sneak into lodging without waking nearby sleepers, or using enclosed parking garages without fouling the air inside, but is generally not a more efficient way to use gasoline.

Yes, the engine cooling system has a thermostat. I have a ScanGauge-II to display both coolant temperature and RPM, but there are plenty more newer and cheaper OBDII-port engine monitor devices to read and display this information, even over a Bluetooth link to a smartphone.

 

In HV mode the car does this automatically, but on a smaller scale. it will charge and discharge the battery as needed. Toyota has spent more than two decades developing the algorithm to maximize efficiency. Of course you know more about what's ahead of you than the car knows, but it seems unlikely that you will find a way to get significantly better efficiency, but I guess if you like tinkering go ahead and try.

There is no temperature gauge, but I assume a light will come on if it overheats. The car automatically keeps the engine warm, and if you're driving with the heat on in HV mode it will run the engine more to keep it warm enough. I suspect the engine runs cooler than a typical engine for efficiency, since excess heat is wasted energy.

There is no tachometer. It wouldn't be that useful anyway, since the car can vary the load on the engine independent of the RPMs. It presumably tries to maximize Brake Specific Fuel Consumption, which is generally high load at low RPM. It's optimized differently than a normal engine, which is why we only get 95 hp out of 1.8L.

I do wish there were more gauges, but I can understand why they left them out. You don't really need any of that information. I did mention all the omissions in the quality survey they sent me (for example, "have you had any issues with the tachometer?" Yes, it appears to be missing! They must have forgot to install it at the factory.)

If you want to see what the car is doing (including engine RPM), you can get a bluetooth OBD dongle and the Hybrid Assistant app.

There is plenty of uphill power. I recently drove up Freemont Pass and watched the power gauges on Hybrid Assistant. It's a 6-7% grade at 65 MPH and tops out at 11,300 feet. Most of the way up the power from the engine was around 45kW, with minimal power from the battery. I was surprised that the steady state power from the engine could be so high without also charging or discharging the battery. It's a pretty empty road, but if I had to pass someone it still has power to spare. It can borrow some power from the battery (even when the EV portion shows as empty and it's in HV mode) and then replace it by charging a little later.

It's not a fast car, but I have yet to find a situation where it couldn't accelerate. On the same pass in my 2007 Honda Civic (automatic), with the gas pedal to the floor I watched it slow down from 65 to 45 before it "decided" to shift to second gear (I could have manually shifted it earlier). In second gear it can get back up to about 65 before the engine redlines and it's forced to shift to 3rd. Usually it can maintain around 65 in 3rd on these grades, so the engine isn't redlined the whole way up, but it can't accelerate anymore. The manual transmission has closer gearing, so it might do a little better with 3rd being a little lower.

 

But does it need saved battery for these hills? My Gen3 certainly doesn't. Those elevations aren't even that high, well below Vail and Loveland and Iceberg and Beartooth passes. The Prius engine (for Gen3 at least) keeps a very reasonable efficiency to a fairly high power output.

I haven't seen the Gen4 BSFC chart, but previous Prius generations vary the engine load primarily by varying engine RPM, not independent of RPM. Their BSFC charts, especially for Gen3, show a very wide plateau of near-peak efficiency. They mostly stick to a fixed operating load line running right through the top of that zone, at fairly high torque, all the way from near-idle to fairly high RPM.

So for any given elevation (air pressure), and very unlike non-hybrids, Prius engine RPM ought to be a reasonable proxy for engine load or power output.

 

My Prius has not been on all those passes, some were in a previous car. But its been on some of them, and plenty of other Prii have been over all of them.

I have had my Prius higher than those, most of the way up Pikes Peak. It didn't get all the way up due to a snow closure at 13,000 feet, so we had to leave it behind and walk up the final pitch. But numerous Prius owners here have driven all the way to the tops of Pikes Peak and Mt. Evans, both over 14,000.

 

Other than running out of gas due to one's recklessness and/or inaccurate fuel gauge, there may be other emergencies in which a gas can can prove handy. Like "being stuck in a remote area", which you mentioned earlier