Hi Tom,

I assume you mean the Lexus IS 300h of the same era? The one major difference is that the Mercedes is a plug-in hybrid, so you'll only get the best out of it if you plug it in to charge up the battery as often as possible. If you don't have an easy way to do that at home or at work then it's probably not the car for you.

If that's not an issue, then you'll find that the Mercedes has considerably higher performance, despite the fact that it's a heavier car. It also has a lower official CO2 emissions rating. They have a similar amount of interior space, though the Lexus generally is of slightly higher quality. The Mercedes has a smaller boot, though.

I'd suggest you go test drive an example of both and have a good poke around to determine which you like best.