Sadly, once risen from its induced slumber and used to its full potential, the engine is omnipresent. Given how eager most economy-focused powertrains are to get you into the highest gear possible, the CLA 250e holds onto revs more than you would expect and in doing so exposes its biggest weakness. Once wound up above 3500rpm, the engine’s refinement is poor, both in terms of noise intrusion and vibration felt through the controls.
The surprisingly loud turbo whoosh would excite in a hot hatch, but in the context of this car and combined with the resonant, booming drone of the engine, it just seems uncouth. It’s disappointing enough in the lower pure-petrol models but particularly frustrating in a car knocking on the door of £40,000.
That’s a shame, because outright performance is respectable enough. The electric motor serves to boost torque and reduce lag, so initial response and urgency is good, and once in the mid-range, the combination of power sources make the CLA 250e feel pretty brisk. But there are two things getting in the way of it being in any real way enjoyable to drive.
The first is the gearbox. The economy bias of its tuning and the complexity of the powertrain makes it sometimes unsure of itself, either responding too aggressively to a throttle input by dropping down too many gears or taking too long to pick a cog and fire you away. Manual mode isn’t much better, because paddle-prod downshifts are sluggish.
The second is the braking system. As noted when we drove the A250e earlier this year, there’s an adjustable regenerative system that defaults to ‘auto’ in hybrid mode. This means it uses data from the sat-nav and forward-facing sensors to decide for itself how much regeneration you might need at any given moment. Clever though it is in theory, the result is a highly unpredictable response to lifting off the throttle: sometimes there’s no regeneration whatsoever when you want it, and other times there’s loads when you don’t.
This, combined with a brake pedal that lacks feel and responds inconsistently as it tries to juggle regenerative and friction power, makes for a plug-in hybrid that’s actually quite tricky to drive smoothly at times.
The CLA’s chassis is one that lends itself to a more relaxed, detached gait anyway. Our car was fitted with the comfort suspension often, albeit combined with rather chunky 19in wheels. The result is what initially seems to be quite a soft and plush ride – one that trips up only over the sharpest surface imperfections at lower speeds.
When little is demanded of it, the CLA is largely vice-free, with numb but predictable steering and decent grip. Press on, though, and it unravels. The soft set-up translates to a bouncing, underdamped feel on faster, undulating country roads, with a substantial amount of body movement for a relatively small and low car. Understeer also becomes the defining trait pretty quickly.
The harder you push, the more it feels loose and heavy. Perhaps that’s no surprise when we’re talking about a car that weighs more than 200kg over the pure-petrol CLA 250. That wouldn’t be so bad if the ride maintained its composure, but it doesn’t feel particularly controlled once you’re out of town.