GreenHybrid - Hybrid Cars - View Single Post

Tim K · #3 (**permalink**) 01-05-2007, 07:34 PM

Actually, for the most part, the low mileages reported are a result of NORMAL conditions that exist with these vehicles. The reason that many reponses are short and/or reference other posts and articles, are because the same questions get asked repeatedly just like on every forum on the internet. I would say that the top reasons for low mileage are simply due to drivers not understanding the vehicles. Also, keep in mind that for a typical driver NO vehicles are going to even come close to EPA fuel economy numbers. If I drove my Mariner Hybrid like I drove my old Grand Cherokee I'd probably be getting around 25mpg too....instead I'm closer to 30mpg.

In no particular order (other than the order they popped into my head), here are my top 5 reasons for reduced fuel economy:

1. Cold temps: Cold temperatures will affect battery/vehicle performance. It will take longer to get up to speed and the battery will not perform as efficiently as it does in its optimum range. Also, many states use "winter blends" containing up to 10% ethanol. This reduces fuel economy further as ethanol has less energy than the equivalent amount of gasoline.

2. Hot temps: Again, we are dealing with optimum temperature ranges for the battery. The difference with heat is that high temps will kick in the AC system to cool the battery thus greatly reducing fuel economy. Also, people tend to run the AC (see #3) or drive with open windows in the summer which will reduce MPG as well.

3. "Red modes": MAX AC, and both defrost settings are labelled in RED to indicate that they when used, the ICE will not be shut down allowing EV mode. This is detailed in the manual. Leaving the defroster on in the winter will keep the engine running even at stop lights....without idle shutdown these vehicles lose one of the major factors in their improved economy.

4. Short trips: Numerous short trips will reduce mileage especially when combined with other mileage reducing items as listed here. Every time the key is turned off, the engine must restart and run until the CAT reaches temp. This may only last 30 seconds or as much as 6-7 minutes depending on temps and how long the vehicle sat, but this can easily account for poor fuel economy, especially if someone makes 6-7 rips an hour apart from each other thereby letting the engine/CAT cool down each time.

5. New Vehicle: These vehicle have break-in periods that are clearly detailed in the manual. It even says in print NOT to even look at your fuel economy for the first 1000 miles (maybe more). Anyone who has driven an FEH or MMH for more than 5000 miles will tell you that they experienced greatly improved fuel economy and greater EV mode capability after 1,000....3,000....and 5,000 miles. I know I did.

Obviously, there are other causes for low mileage and many of them are due to driving habits like cruising at 75mph or hard acceleration. However, the vast majority of "Why am I only getting 24mpg" posts can be answered by one of the above posts. There are very few cases I've seen where there was actually something wrong with the vehicle.