My friend recently purchased a 2021 RX 350 gas model with less than 5k on the odometer. The car now has 10k miles and when accelerating on the freeway onramp or highway speeds there is a an exhaust like odor inside the car.

She took the car to the dealer who confirmed the odor from the test drive and told her the cause of the odor might be sediment in the fuel tank from the previous owner not driving the car very often and/or at highway speeds. The service manager offered no solution except to drive the car more aggressively and maybe the sediment will dissipate and eliminate the exhaust odor.

If this theory is correct, then why not drain the fuel tank and purge the fuel system under factory warranty instead of making the owner suffer driving the car with a pungent odor?

Any input is greatly appreciated.

 

Sounds like the service manager didn't want to be bothered so he invented a reason. I suspect the rear liftgate is not sealing properly, perhaps due to previous body repair. There is a slight vacuum created at the rear of most SUVs and other vehicles that gets stronger at higher speeds, That can suck exhaust fumes into the cabin. If possible, go to a different dealer (preferably one that has a body shop) and ask them to examine the alignment of the rear liftgate. Stress that you believe it is a safety issue and escalate it up to Lexus corporate if the dealer won't help

 

Try another dealer... or ask to speak to the Manager of the dealership.

I had a recall on my 2015 IS250for carbon build up. Long story short, the SM claimed he did not note the car shuddering on start up and wanted to give me back my car after 3 days. I was PISSED and was not very quiet about it. So he said he would keep it another 2 days. Miraculously, I got a call the next day they noted the issue and would do the recall service.

 

Could also be a faulty exhaust gasket leak somewhere in the line... There may be some additional noise (fluttering) with that.

I'd also second Volley's theory on a poor lift-gate seal.