# Fuel Efficiency - Does having to buy premium gas counteract a better mpg?

My grandma passed away last month, and my parents informed me that my wife and I are inheriting her 2010 Chevy Impala. It gets about 24 mpg on the highway, and takes regular gas. However, my dad offered his 2001 (03, maybe) Acura TL instead, due to it’s 30 mpg, and it’d be cheaper on insurance. The thing is, the TL requires premium gas. Does the cost of the premium gas actually counteract the better fuel efficiency?

Leaving aside the question of whether the Acura really needs premium, this is a simple math problem. For every 1000 miles you drive, the Impala will use 41.66 gallons of gas and the Acura will use 33.33 gallons of gas. That means you save money as long as the cost difference is 25% or less. That is, if regular gas is \$4/gallon, you save money as long as premium is less than \$5/gallon.

There are obviously a lot of other issues here. A new Impala will not be as reliable as a new Acura, but you have to compare a new Impala with a 10 year old Acura. Have you checked the blue book values? The Acura will save you \$15 per 1000 miles in gas cost (using the price where I live) – is that enough to pay for the maintenance that the Acura needs now that the Impala won’t need for a few more years?

Well, he did about \$1000 in maintenance this past year, so I think the Acura will be good for a few more years as well. However, it does have just under 100k miles, so I’m not sure what maintenance will be need in a few years anyway.

I’d go for the newer car, the gas costs aren’t much different. I’d be surprised if the TL averaged 30 mpg, anyway. Do you drive huge nuber of miles?

Edit - the EPA web site list the combined mpg rating for the 2001 TL as 20 mpg, and 21-22 for the Impala. So I bet the TL will cost you more for gas, and it’s 9 years older. I’d take the Impala.

We do when we go to visit family. Her family lives 250 miles away and mine lives 750 the other direction. Other than that, we live in a small town that is 5 miles across. (So no for the general commute.)

I’m not sure what maintenance will be need in a few years anyway.

The engine, radiator, transmission, struts, ball joints, CV joints, muffler, catalytic converter, etc etc are all 9 years older on the Acura than the Chevy. Plus the Chevy is worth at least twice as much. It seems odd that your dad would make this offer. Have you always lusted after his Acura? Lust is usually illogical. What does your wife think?

Hah, side note: While I’ve learned to ease up on my lead foot ever since I started having to buy my own gas, I’m sure my dad still gets better gas mileage than me, no matter what car is being driven. So the Impala probably is a better choice. Thank you!

Edit: Yes, I’ve always enjoyed driving the Acura (especially since it’s automatic, but you can shift manually if you like.) My wife prefers the Impala. (She’s going to read this thread and say “I told you so.”)

If your wife prefers the Impala then I’d say that pretty much settles it once and for all.

cigroller September 12 Report:

“If your wife prefers the Impala then I’d say that pretty much settles it once and for all.”

``The wise man knows that cigroller is right.``

Hey, Dad wants the Impala. That should tell you something.

Anytime your wife and your father agree, you should pretty much figure they’re probably right. laughs

Seriously, though, the Impala is probably still under warranty as well.

I’d just like to point out that, regardless of the vehicle make or model, the only reason you would want to buy premium is if the manual says the engine requires premium, if the manual doesnt say, you could guess what fuel grade it needs by its compression ratio, generally anything above 9:1 will need premium though there are many exceptions. The reason behind this is that gasoline will self ignite under pressure (like diesel) the higher the octane the higher the pressure has to be before the mixture will ignite prematurely causing waisted fuel and possibly damage to the engine, the advantage of using a higher compression engine is the amount of power you get out of a given amount of fuel.

I am not a certified mechanic, i just payed good attention in high school auto tech

This ‘white paper’ talks about how Toyota managed to get a 10:1 engine to run happily on regular gas:
http://www.spyderchat.com/1zzfe.pdf

Nice paper, thanks for the link. I love learning new stuff!

Don’t let white paper or car manual to fool you, the only different between regular gas and premmium is the chemical and preserv used by the gas company to make high profit and competition. I have been use regular gas 87 since I got my first car at 1980, Im over the hill still use regular gas, and I never had any problem with new or used car.
I can not tell you about BMW, SABB or those rich and fame’s car, but Toyota, Honda, Montel carlos, Ford, Mecury, etc. I used regular gas all the time and never got a problem, it save me alot money specially nowaday.

Read the manual. I cannot stress how much info the manual gives you. If you don’t have one, get one.
On a side note, I believe Acuras require premium. You can listen to Piky and gamble on whether or not you’ll need a new engine in a year, or you can follow the manual, written by teams of engineers that built the car. I think you can throw in a bit of regular if premium is not available to get you to the next gas station that has premium.

re compression ratio and fuel grade:

Mazda is coming out with a new engine that gets a whopping 14:1 ratio that will run on 87 octane. The Skyactiv gas and diesel both have a 14:1 ratio.