The Frinkosonic MHV comes from the 8th episode of season 24, “To Cur with Love“. The episode begins with Professor Frink demonstrating the Frinkasonic MHV vehicle (the spelling in the game differs from the spelling in the epsiode) which runs off sound waves instead of fuel. However, he loses control of the car and it eventually crashes into the Springfield Retirement Castle. As a result Grampa has to move into the Simpsons house for a while. Here’s how the Fink’s super car looks in that episode:

So is it worth 35 donuts? Like all the other vehicles it doesn’t move. It’s sole purpose is to add 0.75% to your cash and XP collections on rent and jobs – and to look good parked somewhere in your town, as you can see in this screenshot:

There are two problems with it, though:
1. For only 5 donuts more, the Police Car, the Burns Limo, and the Channel 6 News Van add 2% to your bonus multiplier (although for 5 donuts less, the Ambulance only adds 0.5% more).
2. Unlike the Limo from the Respectable Moe promotion of a couple of weeks back, there are no new tasks for Frink or anyone else that allow your characters to interact with it.

But, it’s a limited-time item – and if you’re a fan of Frink, it’s almost certainly worth buying. And if you really like Frink, as with all vehicles, you can buy more than one.