I’m experiencing poor fuel economy with my recently acquired 2001 Lexus Is300. Purchased from the original owner’s family with only 38,000 miles four months ago, the car now has 42,000 miles. While the car runs smoothly without any performance modifications, the gas mileage has been consistently disappointing, even with conservative driving habits in mostly city conditions. To accurately track this, I’ve been meticulously recording fuel consumption at each fill-up. Below are the details of my fuel economy logs:
Fuel Economy Data Log
| Date |
Mileage |
Gallons |
MPG |
| 11/16/17 |
41155 |
11.943g |
15.74 |
| 11/21/17 |
41298 |
8.470g |
16.88 |
| 11/30/17 |
41440 |
11.341g |
12.52 |
| 12/8/17 |
41626 |
13.132g |
14.16 |
| 12/18/17 |
41778 |
12.045g |
12.62 |
| 12/24/17 |
41970 |
13.172g |
14.58 |
| 1/2/18 |
Tires |
New Tires |
|
| 1/3/18 |
42122 |
11.505g |
13.21 |
| 1/15/18 |
42301 |
13.411g |
13.35 |
| 1/21/18 |
42405 |
7.910g |
13.15 |
After noticing a consistent trend of poor mileage in the last three fill-ups, I initially suspected the winter fuel blend. However, Southern California’s climate remains mild, rarely approaching freezing temperatures, making this explanation less likely. In an attempt to improve the fuel economy of my 2001 Lexus IS300, I’ve already undertaken several maintenance steps.
Maintenance Performed to Address Fuel Economy
To try and rectify the poor gas mileage, I have already completed the following maintenance tasks:
- Engine Oil Change: Replaced the engine oil with full synthetic Valvoline at Sears Auto Center.
- Fuel System Decarbonization and Throttle Body Clean: Performed by Firestone.
- Mass Air Flow (MAF) Sensor Clean and Air Filter Replacement: I personally cleaned the MAF sensor using CRC MAF cleaner and installed a new air filter.
Despite these efforts, the fuel economy of my 2001 Lexus IS300 has not improved, and I am still seeking potential solutions. There are a few suggested remedies that I have not yet explored, primarily due to cost or time constraints.
Potential Issues and Suggested Remedies
Based on advice received, the following potential issues could be contributing to the low MPG in my 2001 Lexus IS300:
- Spark Plugs: Replacement of spark plugs was suggested, with the idea that modern spark plug technology might offer better efficiency compared to the original 2001 plugs.
- Oxygen (O2) Sensors: Concerns were raised about potentially failing O2 sensors, even without triggering a Check Engine Light (CEL). It was suggested that O2 sensors could degrade in performance by 42,000 miles.
