I have a Saab 9-5 which has alot of trouble on the highway. When in the city I have to give it alot of gas to go anywhere ( has to rev to 4k to get to 40). Uphill is bad as well. Just replaced the plugs and the Direct ignition cartridge but nothing helped. I even lose speed on the highway with the cruise control on.
Only gets around 8 mpg max
I can only get to 60 max on the highway and have replaced all spark plugs and the DIC. But still underpowered.
If the car has an automatic transmission then maybe it’s slipping. (bad news)
Other than the transmission it could be a sign of a clogged catalytic converter.(pricy)
The car is an '05 and if it has less than 80k miles emissions warranty will pay for it.
As to the converter, this can easily be checked with a vacuum gauge. (if you can find a mechanic who actually uses one and knows how to read it.) It’s a very simple process.
Automatic transmission or manual trans?
it is a 2.0 automatic
8 mpg, and you’re still driving it?
Why?
Have you checked the transmission fluid level?
I really hope that I am wrong, but I strongly suspect that your transmission has never been serviced, and it is now fried as a result of recent driving patterns.
In other words, when it began to rev to 4k at 40 mph, you should have had it towed directly to a transmission shop, rather than keep driving it and destroying the friction surfaces in the transmission. Instead of a cheaper repair, you are likely now looking at a total rebuild of the transmission.
Before you wind up stranded, have it towed to an independent transmission shop.
Do NOT take it to AAMCO, Lee Myles, Cottman, Mr. Transmission, or any other chain unless you want to be overcharged for poor quality workmanship.
Check engine light on? If yes what are codes?
I’d say have the catalytic converter checked for excessive back pressure.
no light, no codes
What would cause this kinda of behavior?
That is another good possibility.
However, that bit about having to rev the engine to 4k RPM in order to get the car to 40 mph concerns me and makes me wonder about the transmission.