As the other attorneys have mentioned speeding 40 or more over the speed limit is a Class A misdemeanor (non-supervisionable). It is important that you speak with an attorney, many of us offer free consultations. Fines and court costs can range widely and depend on a variety of factors. Although by no means guaranteed, it may be possible to have the charge amended. More information on aggravated speeding in Illinois is available at the links below.
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I agree with the others: this is a Class A misdemeanor (the most serious misdemeanor, the same as DUI, battery or retail theft, for example) and you can be sentenced up to 364 days in jail and/or a fine of up to $2,500 (plus fees and costs). If found guilty, you cannot receive supervision, meaning that you will be a convicted criminal. You need to get an attorney who can try to defend this case or get the charge reduced.