does any one here use 'normal/regular' gas in there car on a day to day basis?

Any problems?

I drove my previous car....a 1997 STS on regular 87 octane for 3 years.........i never even knew it needed the good gas. -- But i never had any problems.

Apart from performance related issues...is there a 'danger' to use 87 octane in the TL/TLS?

you're endanger of the engine "knocking." it states in the manual use 92 octane or higher... so i would suggest do what the manual says?

The theorists say use 91 octane. they also say that the warmer climates require higher octane fuel because of the vaporization effect. I know that running 89 is no problem. And we live in a semi tropical climate. The system will ,and does adjust.

the car has knock sensors that retard the ignition timing to prevent the fuel from auto-igniting.

this:
1) reduces performance

and

2) creates more heat.

so over the long term, the extra heat created reduces the longevity of the engine components.

so if you leased it and don't care about performance or engine longevity, go ahead and use less than premium fuel.

This has been discussed to death. Just use what you feel comfortable with. You will get slightly decreased performance, but as long as you're not racing every chance you get, you wouldn't really worry about it anyways. So go ahead and use whatever fuel suits your budget and/or conscience.

I went with premium or what the manual recommended.
I figured the difference (in KC) between 89 & 91 octane is $0.20. I average 15,000 miles a year.
I get 20 mpg (hi-way & city mix)
I use (15,000/20)=750 gallons a year
My increased expenditure is (750*$0.20)=$150 per year
or $0.41 a day.
Offset this minimal expenses by drinking 1 less Coke a day.

(just me)

I put 94 octane from Sunoco in my car. The way I figure it, I have a Company gas card and putting the more expensive fuel in my car costs me nothing, so what the hell.