Can I use regular?
read your manual, but i doubt you can run regular. they build those cars for performance as well as comfort. regular will probably give less fuel mileage and performance as well as void your warranty.
Read the manual. It will tell you. If it says you must use premium, you may damage the engine if you use regular. If it says you should use premium, it means regular will not likely damage the engine, but it will reduce power and will reduce mileage and may not end up saving you any money in the long run.
You bought a Lexus and want to skimp on the gas for it?
It’s 3.5L v-6 with a 10.8:1 compression ratio. Even oin their website, Lexus tells you to use 91 octane fuel
Ratings achieved using the required premium unleaded gasoline with an octane rating of 91 or higher. [i]If premium fuel is not used, performance will decrease.[/i]