I came from a 16 IS350 luxury package, not f-sport, and now driving the G70 for the past 3 months, my mom is driving the IS now. What I am going to say is based on my experience with my 16 IS350 non f sport.
Fuel consumption:
When driving both in eco mode, g70 is better by a slim margin, I really mean slim, 12.5 L per 100km vs 13.3 L in the IS.
When having fun, IS is better in this department. Lexus runs on premium, G70 can run on both premium and regular, it has the same engine has the
stinger. I did feel a tinnnnnny bit of the boost coming I'm a tiny bit earlier when running in shell 92. I do mostly city driving, maybe 10% highway, maybe.
Power:
G70 wins hands down. IS is no turd by any means, it has 306 hp on a NA V6 but u have to really rev it up to put a smile on your face. G70's turbo comes in down low. One of my main complaint with the IS is it's low rev power, the car feels slow and heavy in eco mode, sport mode is not bad but u really can't compare it to a turbo v6. But when u rev it up, u wil l smile, especially with the engine grunt. Handling wise both car feels pretty good to a regular driver like myself. The IS and the Caddy ATS' handling are rated pretty high in the compact sports sedan segment, according to many reviewers.
RIDE:
I kinda miss the cushy leathers in the IS. The NAPA leather in the G70 is supposed to be nicer, but I find it not as cushy as the IS. My IS did not have the adaptive suspension, it rides softer than the comfort mode in G70. Rear seat leg room is a bit better in the Lexus.
Road noise:
IS is quieter. It's a Lexus after all.
Reliability:
Too early for me to tell. No problem with either car, maybe Lexus wins because it is a Lexus.
Tech: G70 hands down. Yes I know my IS is 2 years older but I think even the new ones don't have 360 camera,
apple carplay Android auto,
adaptive headlight, it doesn't even have a sunglasses holder. BUT IS has a nice 10 inch wide screen, and I may be the odd one here but I actually like the mouse pad control in my IS better than the G70's touch screen. Oh and g70 has HUD and folding mirrors which the lexus lacks.
Design:
I like both. People hate the predator grill in the IS but I like it better than the Germans. IS will get a new design sooner than the g70, in a year or 2 supposely. G70 does have a larger sunroof I will give them that. Interior wise, maybe IS is more refined, but I have no problem with either.
Value:
If u can get a fully loaded is350 fsport for 40k full loaded it is a good value, vs spending 12k more for the g70 according to US price? U do get a lot more in the g70 but only u can tell if it is worth the 12k. I don't know about the resell value down the road, maybe lexus holds better value? I really dont know.
