Question about auto start/stop
Advanced
Joined: Jul 2016
Posts: 633
Likes: 227
From: NC
Your priorities and your choice. Guess I'm going to find out on my new 2026 Lexus TX500h. It's a hybrid and the whole point is that the electric system (traction/HVAC, etc.) takes over with the engine OFF when stopped or in slow traffic. With our 2023 RX350, we just shut start/stop mode off when it becomes annoying, largely because HVAC pretty much stops working when the engine quits AND there is a lag in acceleration from stopped when the engine restarts. Not so on the hybrid - it just "GOES" and the HVAC is always active, engine "ON" or not..
These two cars should be "poster children" for relatively heavy cars with stressed turbo-4 engines and start-stop modes. We'll see how they stand up. So far the 2023 RX350 has been trouble free (2WD gas Luxury edition). My 2008 Toyota Sequoia Platinum 5.7L V8 carried me and my family around in total comfort for 17 years with just routine maintenance. Still looked great in and out when I traded it in for the TX 500h. Same with our older 2010 RX350 2WD Lux - still going strong, still looks great. So the two NEWER Lexus vehicles have a LOT to live up to. I will say the the new vehicles are quicker, more agile and way more fuel efficient than their predecessors. And way, WAY more complex.
One precaution we do take is regular oil changes at intervals no longer than 5,000 miles, or at least twice as often as Lexus recommends. I don't know what they were thinking bumping it up to 10,000 miles. That's ridiculous. A 2.4 liter Turbo-4 ICE producing 275 HP and 317 Ft.-lbs. of torque while running an 11:1 compression ratio and 12 lbs. of boost is going to beat the heck out of ANY oil.
These two cars should be "poster children" for relatively heavy cars with stressed turbo-4 engines and start-stop modes. We'll see how they stand up. So far the 2023 RX350 has been trouble free (2WD gas Luxury edition). My 2008 Toyota Sequoia Platinum 5.7L V8 carried me and my family around in total comfort for 17 years with just routine maintenance. Still looked great in and out when I traded it in for the TX 500h. Same with our older 2010 RX350 2WD Lux - still going strong, still looks great. So the two NEWER Lexus vehicles have a LOT to live up to. I will say the the new vehicles are quicker, more agile and way more fuel efficient than their predecessors. And way, WAY more complex.
One precaution we do take is regular oil changes at intervals no longer than 5,000 miles, or at least twice as often as Lexus recommends. I don't know what they were thinking bumping it up to 10,000 miles. That's ridiculous. A 2.4 liter Turbo-4 ICE producing 275 HP and 317 Ft.-lbs. of torque while running an 11:1 compression ratio and 12 lbs. of boost is going to beat the heck out of ANY oil.
I do the same manually turn it off when annoyed. My 2024 TX350 has been pretty good minus the small gas tank. Not a deal breaker for me.
Driver
Joined: Dec 2025
Posts: 71
Likes: 34
My new TX 500h has a 17.2 gallon tank and I was VERY concerned, based on some forum posts, that I could only use about 12 gallons or so, which WOULD be a problem. Not so, First fill, 16 gallons went in, second fill 16.1 - just using the fast fill fuel pump latch notch followed by the slow fill notch. Pump clicked off at 14.75 on fast fill and off at 16-16.1 gallons on slow fill. I do this with ALL my cars. This was after running down to zero range ("REFUEL NOW") about 15 miles after the LOW FUEL banner came on (at 7 indicated miles of range). Usable range with lots of short trips in the city has been about 315 miles/18.3 MPG. This is compared to 11.3 MPG in my last car (5.7L V8 Sequoia Gen II). So I'm OK with it but hope city MPG will improve a bit over time. Have not taken it on long highways trips yet - only 680 miles on the clock at this point. On longer trips in heavy holiday Los Angeles city traffic, the TX 500h manages about 23-24 MPG, including engine warmup. But constant shorts trips (3-5 miles) from dead cold with many warmup cycles seems to be the MPG Achilles Heel of this car, as it is with most, gas, hybrid and even electric vehicles.
I'm hoping for at least 400 miles of highway range to start with, which would be just 25 MPG based on my own fuel tank capacity experience. Independant Youtube tests say the TX 500h should hit about 27 highway MPG once broken in, and that'll work for me.. My 2023 RX 350 Luxury (gas ony) started off at about 27 MPG at this point (less than 1K miles) and improved to about 29.5 by 10K miles. (same trips - L.A. to Vegas and back - 600 miles).
Last edited by Stonebender; Dec 28, 2025 at 11:19 AM.
Rookie
Joined: Jun 2025
Posts: 32
Likes: 9
Do you have any idea what technology and mechanics are involved to get the start system to work? Do you realize that starters have only x number of cycles built into them? I can't even begin to respond to your other comments. You obviously have no knowledge of how cars function (evidenced by the fact you purchased a Volvo).
Modern stop/start systems are pretty well designed, with upgraded components like robust starters, heavy-duty batteries, and low-friction engine parts to handle numerous shutdowns and restarts. The engine times its shutdown so the crankshaft stops at the point where it takes the least amount of effort by the starter to turn and restart the engine. The starter, alternator, and battery on cars with auto stop/start will be more robust than similar cars without the feature. That means they're far more likely to not experience significant wear via the operation of the system.
As for saving fuel-- yes, it will save fuel, but how much depends on how much the system is used. The old "it takes more fuel to restart the engine than leave it idling" is a myth left over from the days of carburetors. Modern fuel injection systems use a precise amount of fuel injected into the engine for startup, as well as normal operation. There's not a significant amount of excess that's left over like on a carbureted engine. In short, whenever a fuel injected engine is running, it's burning fuel. When it's not running, it's burning no fuel.
Some people don't like auto start/stop because they feel the car doesn't respond as quickly due to the engine being shut down. Invariably they tend to be EXTREMELY shitty drivers-- the kind who like to stab the gas as soon as the light turns green, cut you off by making a left turn right in front of you, and other immediate-action type of driving behaviors.
If manufacturers are having issues with longevity of components in cars with start/stop systems, that's just lazy engineering. Not a problem with start/stop systems.
Advanced
Joined: Jul 2016
Posts: 633
Likes: 227
From: NC
Hmmm. Small gas tank? You should have a 17.8 gallon tank - not that big but not too bad, either.. Is there a fill or LOW FUEL warning issue? If so, try slowing the tank fill rate as it approaches full - AND there might be a firmware update (that you might have to explicitly request from the dealer) for your TX that makes the warnings less aggressive.
My new TX 500h has a 17.2 gallon tank and I was VERY concerned, based on some forum posts, that I could only use about 12 gallons or so, which WOULD be a problem. Not so, First fill, 16 gallons went in, second fill 16.1 - just using the fast fill fuel pump latch notch followed by the slow fill notch. Pump clicked off at 14.75 on fast fill and off at 16-16.1 gallons on slow fill. I do this with ALL my cars. This was after running down to zero range ("REFUEL NOW") about 15 miles after the LOW FUEL banner came on (at 7 indicated miles of range). Usable range with lots of short trips in the city has been about 315 miles/18.3 MPG. This is compared to 11.3 MPG in my last car (5.7L V8 Sequoia Gen II). So I'm OK with it but hope city MPG will improve a bit over time. Have not taken it on long highways trips yet - only 680 miles on the clock at this point. On longer trips in heavy holiday Los Angeles city traffic, the TX 500h manages about 23-24 MPG, including engine warmup. But constant shorts trips (3-5 miles) from dead cold with many warmup cycles seems to be the MPG Achilles Heel of this car, as it is with most, gas, hybrid and even electric vehicles.
I'm hoping for at least 400 miles of highway range to start with, which would be just 25 MPG based on my own fuel tank capacity experience. Independant Youtube tests say the TX 500h should hit about 27 highway MPG once broken in, and that'll work for me.. My 2023 RX 350 Luxury (gas ony) started off at about 27 MPG at this point (less than 1K miles) and improved to about 29.5 by 10K miles. (same trips - L.A. to Vegas and back - 600 miles).
My new TX 500h has a 17.2 gallon tank and I was VERY concerned, based on some forum posts, that I could only use about 12 gallons or so, which WOULD be a problem. Not so, First fill, 16 gallons went in, second fill 16.1 - just using the fast fill fuel pump latch notch followed by the slow fill notch. Pump clicked off at 14.75 on fast fill and off at 16-16.1 gallons on slow fill. I do this with ALL my cars. This was after running down to zero range ("REFUEL NOW") about 15 miles after the LOW FUEL banner came on (at 7 indicated miles of range). Usable range with lots of short trips in the city has been about 315 miles/18.3 MPG. This is compared to 11.3 MPG in my last car (5.7L V8 Sequoia Gen II). So I'm OK with it but hope city MPG will improve a bit over time. Have not taken it on long highways trips yet - only 680 miles on the clock at this point. On longer trips in heavy holiday Los Angeles city traffic, the TX 500h manages about 23-24 MPG, including engine warmup. But constant shorts trips (3-5 miles) from dead cold with many warmup cycles seems to be the MPG Achilles Heel of this car, as it is with most, gas, hybrid and even electric vehicles.
I'm hoping for at least 400 miles of highway range to start with, which would be just 25 MPG based on my own fuel tank capacity experience. Independant Youtube tests say the TX 500h should hit about 27 highway MPG once broken in, and that'll work for me.. My 2023 RX 350 Luxury (gas ony) started off at about 27 MPG at this point (less than 1K miles) and improved to about 29.5 by 10K miles. (same trips - L.A. to Vegas and back - 600 miles).
Driver
Joined: Dec 2025
Posts: 71
Likes: 34
My 2023 RX 350 (gas) is NOT so smooth, there is a delay and the AC stops when the engine does, unlike the TX 500h which has electric AC
Driver
Joined: Jul 2012
Posts: 71
Likes: 46
From: PA
Couldn't disagree more. I think it all comes down how well the manufacturer implements the start stop system.
The first generation system in my dad's Audi A8 from over 10 years ago was awful. Downright dangerous at times.
On my 2024 Volvo, the difference between being the engine being on vs off is basically imperceptible. That's the standard we should judge against.
It's the same way with pure EV's. Toyota's BZ4X and Dodge's Charger EV (or any Stellantis product in general) are not just terrible EV's, they're terrible cars. I wouldn't judge EV's by the worst example of them.
The time when a vehicle is stopped, you're literally getting 0 miles per gallon. Why wouldn't you want to save some money?
The first generation system in my dad's Audi A8 from over 10 years ago was awful. Downright dangerous at times.
On my 2024 Volvo, the difference between being the engine being on vs off is basically imperceptible. That's the standard we should judge against.
It's the same way with pure EV's. Toyota's BZ4X and Dodge's Charger EV (or any Stellantis product in general) are not just terrible EV's, they're terrible cars. I wouldn't judge EV's by the worst example of them.
The time when a vehicle is stopped, you're literally getting 0 miles per gallon. Why wouldn't you want to save some money?
Rookie
Joined: Jun 2025
Posts: 32
Likes: 9
One reason is because manufacturers gatekeep technology behind higher trim levels.
There's no reason why you should have to spend 80k+ to get a PHEV powertrain in a Toyota 3 row SUV.
You can't get a PHEV powertrain in the Grand Highlander, which is the only reason I bought a TX.
I would much rather have bought a GH Hybrid Limited in the 55-60k range if they had offered it with a PHEV. But they don't.
Volvo does the same thing. In the US they only offered my V60 in the top of the line Polestar trim as a PHEV. And they only offer the V60 CC in a mild hybrid.
Whereas in Europe they offer multiple cars with multiple (affordable) trim levels with a PHEV powertrain.
It's a choice that manufacturers are making.
There's no reason why you should have to spend 80k+ to get a PHEV powertrain in a Toyota 3 row SUV.
You can't get a PHEV powertrain in the Grand Highlander, which is the only reason I bought a TX.
I would much rather have bought a GH Hybrid Limited in the 55-60k range if they had offered it with a PHEV. But they don't.
Volvo does the same thing. In the US they only offered my V60 in the top of the line Polestar trim as a PHEV. And they only offer the V60 CC in a mild hybrid.
Whereas in Europe they offer multiple cars with multiple (affordable) trim levels with a PHEV powertrain.
It's a choice that manufacturers are making.
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