I am aware you can get a DUI just sitting impaired in a car with keys in ignition. I have a car with a keyless ignition. I was wondering what the standard for DUI is in this type of car. I do not drink so I may never be subject to a DUI. Just more curious then anything else.
Pennsylvania is one state sometimes cited as having such a law, but the law does not refer to "keys in the ignition", instead,
An individual may not drive, operate or be in actual physical control of the movement of a vehicle after imbibing a sufficient amount of alcohol...
Similarly in Washington,
A person is guilty of being in actual physical control of a motor vehicle while under the influence of intoxicating liquor or any drug if the person has actual physical control of a vehicle within this state...
California law is narrower, since
It is unlawful for a person who is under the influence of any alcoholic beverage to drive a vehicle
and this does not include being in physical control. See Mercer v. DMV which affirms that the person must have been driving, but it is not necessary to witness the person driving. Keys in the ignition can be evidence that you were driving, likewise a warm engine or tires, car is in gear, you're in the middle of the road. I doubt that any law is stated in terms of "keys in the ignition", more likely it reduces to actual driving, or being in control of the vehicle.
Keyless Ignition Probably Just Lowers the Bar For Constructive Control of a Vehicle
The general legal principle would be actual vs constructive: physical evidence vs circumstantial evidence. As popular as some shows have made lines like "they only have circumstantial evidence" – still, circumstantial evidence can absolutely be enough.
In OP's jurisdiction of Minnesota (my own too), for example, State v. Florine, 226 N.W.2d 609 (Minn. 1975) has long been the standard for an aspect on constructive possession, where there is no physical evidence of a possession as an element of the violation of law – but there is substantial circumstantial evidence of a violation. In OP's fact-pattern, the related principle would be constructive control of a vehicle.
OP alludes to those jurisdictions which have allowed keys in the ignition to serve as an element proving constructive control of a vehicle. Meanwhile, if simply pushing a button were enough to effectuate the same act as turning a key, then courts in such a jurisdiction would likely be fine with finding constructive control of the vehicle where a person is simply sitting in the car (with the key fob).