View Full Version : Had the chance to drive a M-B GLA45 AMG

December 31st, 2014, 10:22 AM
I can sum up the experience in just two words: TURBO LAG

I don't get the point of the car even in non-AMG trim; it looks like an Impreza with less cargo-carrying capacity for twice the price. The seats are nicely-bolstered (so much so that it's difficult for a 40-something man to make a graceful exit) and the 200-mph speedo with carbon fiber insert is optimistic but cool. The nav screen looks like someone glued a small tablet to the dashboard and is comically cheap-looking for a Mercedes. I'm very surprised they couldn't do any better than that. If I'm going to spend $50-60k on a car with navigation, I want it to look different than something I might have cobbled up using a dashboard tablet holder from Pep Boys.

But the turbo lag is the big nope with this car. 26-odd pounds of boost will create that, I guess, but it feels far slower than my TSX at around-town speeds. It reminds me of how the carb in my '82 Wagoneer would cause a delay in acceleration that always gave me pause (pun intended) when preparing to turn across a busy street, except in the case of the GLA45, the delay ends with 355hp coming on all at once. The good news is that acceleration-wise, it's the quickest car I've ever driven (sorry, Phil/Drew/Nick), with 0-60 coming in four-something seconds. It's the true "push you back in your seat" kind of power. Definitely not well-suited for around-town driving, although it is fun to scream away from a stop. I could definitely see this car being a lot of fun in the twisties, though I only had a few minutes' time and didn't get to really evaluate the handling.

It's cool - in a Jalopnik kind of way - that the financial case for building a pointless car like this can be made, but if I had to buy a new vehicle with 300+ HP and AWD, I'd just save $12-18k (giving up about 50hp in the process) and get an STi.

Alan P
December 31st, 2014, 10:37 AM
Although I haven't driven one it certainly seems like a lot of 'extra' cash for what you can get simply because it's an AMG Mercedes.

Freude am Fahren
December 31st, 2014, 03:01 PM
I think we had that discussion about the nav screens before, in the AMG GT topic (it has it too). I'm 100% with you on it.

January 1st, 2015, 08:25 AM
People will buy it for the badge, because it's an EUROPEAN CAR and they can't stand being seen in a RICE ROCKET. Seriously.

January 1st, 2015, 09:41 AM

January 2nd, 2015, 12:08 PM
But... did you spank it?

January 2nd, 2015, 02:48 PM
Like a runaway cheerleader.

January 3rd, 2015, 01:49 AM
Had to google to see what car you were talking about... damn, that thing is hideous!
And according to your quick review sucks too. AMG stuff for the sake of AMG narcissism.

Freude am Fahren
January 3rd, 2015, 04:03 PM
To be fair to the MB, it's the best looking of all of the small SUV's in person, IMO.

Say what you will about the segment (it's STUPID), but M-B has done a good job within it, I think. Skinniest kid at fat-camp type stuff here.

January 4th, 2015, 04:27 AM
Don't be silly. Subaru Forester.

March 16th, 2015, 09:01 AM
I test drove the A45 AMG. My initial feeling was....meh! Very, very quick but a very inert chassis and, yes, turbo lag like an '80s Saab. I came away so unimpressed that I thought I'd missed something so went back after a month and tried another one. Same feelings. The 7 speed dual clutch is also one of the very worst I've tried. Kind of glad as I could walk away form spending 40k on a hot hatch!!!

March 16th, 2015, 09:17 AM
I think the super-high boost yields that off-on feeling. A coworker has a C400 which - while it isn't that bad - still feels laggy compared to other modern turbo cars. There just isn't an elegant way to have 20+psi on a single turbo and still have linear power delivery. This is where twin charging or sequential turbos might want to be used, although that adds weight and hurts economy.

March 16th, 2015, 09:35 AM
There is actually a very elegant way to have 20+ psi and linear power delivery: VGT/VNT (http://en.wikipedia.org/wiki/Variable-geometry_turbocharger).

It's complicated and a potential maintenance/reliability headache, of course...TANSTAAFL. ;)

March 16th, 2015, 09:54 AM
I'm not sure that would work out. 26psi on a VNT turbo would be kinda nuts - the EGTs would murder the actuator in very short order.

March 16th, 2015, 09:57 AM
There's a reason they tend to run them on diesels. ;) But still--that's the way to do it, if you can get the materials to stay happy.

Curious what the Porka Turbos ran for boost--that seems to be the newest gasoline example on the wiki page.

March 16th, 2015, 10:07 AM
I'll bet it's in the realm of 10-15psi, but since it's Motronic it's a torque target rather than a boost target. Like, 10psi in cold days and 15psi on hot days.

March 16th, 2015, 10:13 AM
Around 500 lb-ft from just under 2000 rpm to 5000 rpm. From a 3.6 liter. :D :D :D

March 16th, 2015, 10:14 AM

March 16th, 2015, 10:19 AM
Side note: variable vane/nozzle is how hydropower turbines are operated/controlled as well (details vary depending on turbine style). :)

March 16th, 2015, 10:58 AM
I'm not sure that would work out. 26psi on a VNT turbo would be kinda nuts - the EGTs would murder the actuator in very short order.

THat's OK, the Merc drivers won't mind. The Borg Warner turbos they currently use are so sensitive to oil supply and EGT that they're constantly blowing anyway. Reading the A45 section of the UK A Class forum makes me very glad I didn't buy one! Some have blown up on the way home from the dealers!

March 17th, 2015, 10:51 AM

March 18th, 2015, 06:06 AM
You guys are so lucky normal aspiration hasn't died a death due to stupid legislation. I miss it, dearly! Especially my RX8s.

March 18th, 2015, 06:15 AM
Sounds like someone needs a Camaro :up:

March 26th, 2015, 03:32 PM
Except Chevrolet pulled out of the Uk....again....last year!