daryll40

Because there has to be a logical reason that Lexus subjects itself to a significant sales objection. Your random data is very interesting, but it’s not enough to dismiss the manufacturer’s specs for fuel. There has to be an answer.

Freds430

I watched a video clip of an Acura engineer must have been a former Acura engineer that stated the reason is it makes the person buying the vehicle think they are buying a superior engine that only requires the best most expensive gas.

daryll40

Then why doesn’t the current RX require premium? Is it all of the sudden, after 25 years of RX’s, that Lexus needs to arbitrarily up the octane requirement so the vehicle will NOW seem premium?

jer

With some engines ( I believe Mazda has one) Premium is recommended-not required- as it will provide the HP & Torque advertised for that particular engine. If regular gasoline is used, there is no damage caused but the engine also loses some HP. I would think that may be the case with the new engine(s) in the 23 RX.

dibl

The 2GR-FKS doesn't require premium because they took an engine designed to run on 91 octane and added a VVT-iW system to lower the compression ratio sufficiently to burn 87 octane without knocking.

More details on this old thread: https://www.clublexus.com/forums/rx-...l#post11164263

daryll40

Exactly. Lexus WANTED to be able to compete with the vehicle not needing premium gas. So that negates the assertion that there is marketing value in requiring premium gas.

dibl

There's no marketing value in requiring premium fuel in the Crossover/SUV market, luxury or not.

There's marketing value in offering high-performance engines in the premium sports car market, and those buyers don't care what kind of fuel is needed -- premium is expected..

daryll40

I completely agree with this. Which brings the discussion back to the beginning, coming full circle: That the premium fuel requirement for the RX is a dealbreaker for many, perhaps me. And that ignoring the requirement and running 87 octane, despite of good data that it will probably do no harm, isn't the answer for those of us who are too cheap to buy premium. There is a reason Lexus requires premium fuel for the 4 cylinder turbo as well as the hybrid engine, both used in the RX. It's not exactly clear what the reason is, but ignoring it isn't the answer. I might live to be 100 even if I never go to a doctor, but skipping all doctoring isn't the answer.

dibl

The 2022 RX has curb weight of 4,222 lbs. and is powered by a 295HP engine.

https://www.edmunds.com/lexus/rx-350...eatures-specs/

So, unless they are shaving significant weight off the car for 2023, and if they hope to retain the performance that the RX has today, that 4-banger is going to have to be (a) pretty powerful in the first place, and (b) turbocharged, which is in fact the case, to get anywhere near 295HP. High power to displacement ratios are achieved with premium fuel.

daryll40

So this confirms my suspicion that ignoring the 91 octane requirement isn’t wise. And that the 2023 RX will be a dealbreaker for cheapskates like me who won’t buy cars requiring premium gas.

dibl

Besides the premium fuel requirement, there are other reasons to look at that turbocharger with a jaundiced eye, IMHO. I would expect the current 10K mile oil change interval to be cut in half, for example, because turbos are famously sensitive to oil quality.

https://www.motorbiscuit.com/2022-to...gine-problems/

https://www.garrettmotion.com/knowle...chargers-fail/

https://repairpal.com/estimator/toyo...placement-cost

Cocal

Today's 4cyl to do the job that one expects need to run on premium (91 oct Min) any manufacturer that says otherwise is listening to the marketing dept and not the engineering one.
Now if you keep the vehicle for 3 yrs or so you may not see any problems, but if longer you will and so will the 2nd buyer.
There is a good reason why manufacturers recommends premium as they know that this word is = to lost sales.
The resistance to premium I think is psychological rather than $$$ unless one drives a lot. Just my opinion.

toyotaman7

Power ratings of the same engines on Toyota vs Lexus, where they recommend premium fuel in Lexus is typically higher:

2019 Highlander Hybrid - 306hp; same powertrain in RX 450h with premium fuel: 308hp
2022 Tundra 3.5 Twin turbo (Regular Gas): 348-389hp - Lexus LX600 same engine, premium fuel: 409hp.
2023 Highlander 2.4L Turbo; Regular Fuel : 265hp; 2023 Lexus RX 2.4L Turbo - Premium Gas: 275HP

They do squeeze more hp out of the engine by changing the tuning which necessitates the premium fuel.

dklanecky1

Maybe because they don't have to pay for premium gasoline? Even a tiny improvement is worth it to them.

daryll40

So here's what it boils down to: Will the 5thGenRX, with the 4CylTurbo91Octane engine cost the same or less, per mile, to fuel as the current 4thGenRx87Octane engine? Is the efficiency of the 4CylTurbo "enough" better to overcome the extra 15% (current here in Pittsburgh) cost of premium (vs regular)? I can't see how.